Oil cooler on FW instead of raw water side of the cooling system

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Chris Foster

Senior Member
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Messages
280
Location
USA
Vessel Name
Thea
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46 Grand Banks Classic
Knew I was going to have a lot of time to kill a few weekends ago, so I picked up a copy of PM for laughs.

To my amazement, D'Antonio confessed that running an engine at under 80% power might actually not cause instant complete destruction - and he actually made some interesting points (yeah, I'm still kind of in shock).

But seriously... one of the points that he made was low oil temperature when running at low power.* I've always been a little perplexed by the oil coolers on my 6.354s located between the raw water inlet and the pump - so they're typically getting lots of 45 to 50 degree water*pulled through.* In aircraft engines, there's typically a thermostatic valve known as a Vernatherm that only diverts oil through the oil cooler when it gets above about 160*degrees or so.* On the Perks, however, the transmission and lube oil go through the cooler regardless.

One of D'Antonio's suggestions was replumbing the oil cooler to be on the*FW side of the system instead of the raw water.**Now you're using hot water to cool the oil, and you're eliminating any electrolosys issues.* By getting the oil good and warm, lots of the moisture and acids get boiled off.* The oil also runs a bit thinner, which should help fuel burn.

I'm sure there are circumstances where this might result in excessive oil temperatures (typically above 220 degrees).* But with lower power operation in cold water, it seems pretty*straightfoward.

Looking at my engines, there's a tap that comes out at the back of the head that runs to the exhaust manifold to cool its exterior, then exits at the front of the*engine to the water pump inlet.**It looks pretty straightforward to reroute this through the oil cooler first, then to the manifold.

I'm looking for any comments, advice, or other experiences with doing this.* It surely seems to be*a sensible modification.* It would definitely require some*careful measurements with an infra-red thermometer to make certain that*the oils are being kept in a reasonable range, and that the coolant is kept below the boiling point by the time it leaves the exhaust*manifold.**

Thoughts???*
 
I suspect it will depend greatly on the type of engine(s) one has and where one boats. In our waters (PNW) the old, low-tech thumper Lehman 120s seem to reach operating temperature (about 180-190 degrees) at 1500 rpm or so (under load) and it doesn't increase much after that. The oil cooler on a stock Lehman 120 is located immediatly aft of the engine's raw water pump, so it's getting cold water all the time.

I have been told by FL120 operators in places like Florida that with their considerably warmer water temperatures, their engines run hotter than they do up here. So someone who boats down there might want to keep their coolers in the raw water flow rather than the much hotter engine coolant flow.

A modern, higher-speed turbocharged diesel might benefit from having warmer water running through the oil cooler if it was going to be operated at lower-than-normal power settings. But if you set it up this way, what do you do if you decide you want to run at the more normal higher speeds?

Figuring that the marine diesel suppliers probably set their engines' cooling systems up in the most sensible way for the manner in which most of the boats that might use their engines are operated, I tend to lean toward the "if it ain't broke, don't mess with it" school of thought.* I'm not a diesel expert like some of the other folks in this forum, but it sounds to me like D'Antonio is armchair-theorizing again.

-- Edited by Marin on Tuesday 5th of May 2009 10:45:06 PM
 
Good topic Chris.

Vernatherm is a brand name of a thermostat manufacturer. It must be like the infamous Band-Aid, Kleenex and others where virtually everyone uses that brand and the name stuck.

My next question is so we know that the oil isn't at the proper temperature already? I've toyed with putting an oil temp gauge on my Lehman but haven't done it yet. I'm anxious to see what temps you are running now. It seems to me that the oil gets plenty hot already with the standard method of oil cooling described by Marin. I suppose it would be pretty easy to IR the oil filter during a run, I just haven't done it yet.

Ken
 
I'd say don't **** with the way the engine manufacturer set it up.
 
Just bought an IR thermometer the other day to check out a radiant heat system that I installed in a house that I'm bulding, so I'm pretty interested in taking a look the next time*"the girls" are*up to temperature.

Keith - I generally do agree with the "if it ain't fixed, don't broke it" philosophy.* I'm thinking about making an exception this time because the manufacturer presumably set up the engine to keep cool running at full power in 80-degree-plus Florida water.* Running 30-40% power in 50 degree water is another story.

Hoping to get the old girl fired up on Friday (the boat, I mean).* I'm going to go on a limb and*predict 130 degree oil temperature under my typical operating conditions.*
 
"I'd say don't **** with the way the engine manufacturer set it up."


The engine mfg probably thought of the engine as a light duty tractor engine or lorry engine.

It was ****ed with when someone,somewhere "marinized" it.

To select an operating method that will assure longer life in its current use sounds like a GREAT idea to me!
 
Regardless of the cooling medium, you can purchase a thermostatic bypass valve to regulate the oil temperature returning to the engine. These valves cost less than $100 generally and bypass the cooler when below setpoint.

The high performance car crowd use them so there are several versions available.
 
Chris,

I thought about doing the same thing with the oil cooler on my Ford engine when I put the cooling system back together - in fact I just assumed it was run off the coolant circuit till I double checked in the shop manual. In the end though I put it back to sea water for simplicity of plumbing and peace of mind.

It is a nice idea but these engines have been running like this for up to thirty years, mine is 1978, and low oil temp does not seem to have shortened their lives. You are right it probably puts the engine into a more theoretically ideal position when in cold water.*

But if that were having a detrimental effect on the life of the engine would they still be running so smoothly in so many displacement boats after all these years? Based on the long life these engines are showing I tend to agree with Keith.

Most of the damaged Fords and Perkins I see in the six cylinder models are the high HP ones with turbos and after coolers which have not have been suffering from low oil temp - rather overloading and overheating in most cases.

Oil analysis done near to an oil change interval will tell you if your oil is accumulating moisture or acids from cold running.

Cheers, Leon.


-- Edited by Phuket on Wednesday 6th of May 2009 06:25:27 PM
 
"these engines have been running like this for up to thirty years, mine is 1978, and low oil temp does not seem to have shortened their lives. '

This is because they were designed for variable loads , and ideling, as farm equipment frequently requires. 120HP asked to operate at 3gpg (50hp)would be a underload problem IF the engine were a real 120HP industrial unit. A light duty truck engine can take it easily ,for 30 years.

"Most of the damaged Fords and Perkins I see in the six cylinder models are the high HP ones with turbos and after coolers which have not have been suffering from low oil temp - rather overloading and overheating in most cases.'

This is because some dummy believed the add copy , that they could produce big power , at a tiny price.

They can, but not for long, simply look at any engine mfg or converters literature.

There is a HECK of a difference between the short term pleasure boat rating (sometimes 30 min in 24 hours) and a more trawler useful 24/7/360 rating .
 
We have been here before. New input though the bit about Steve DeAntonio. I remember suggesting in the past to take out the oil cooler for guys that run under 50% load but Rick B has a better idea and it should be as dependable as a coolant thermostat. But those of you running at 40% load or less ((2 1/2 gph or less) on a Ford Lehman) have no need for an oil cooler. Keith, If we were to run an engine the way the manufacturer suggests then we should'nt dink w the way it's set up but if we run the engine at extreemly low loads adjustments should be made. Obviously the correct solution to the problem is to replace all those 120 hp engines w 60 hp engines. This is not universally cost effective. One could run those engines at 1500rpm for however many years untill they puke and THEN replace them. Don't be fooled thinking your engine is warm because your coolant is warm* ..* the coolant is artificially kept warm by the thermostat. My Mitsu will indicate 180 degree coolant w no load at all and near idle rpm. Focus on the oil. Marin, I'll bet engine manufacturers, if they were to be reading this forum, would put oil HEATERS and coolers thermostatically controlled to maintain the correct oil tempeture. What don't you guys like about running your engines 75% ? Don't give me this hogwash about being too old and or being not designed for it. I see 1. Noise 2. Vibration and* 3. Fuel consumption as the big issues you might have. Noise and vibration can be relativly easily solved. As for fuel costs check out your total boating expenses and compute what percentage of that cost is fuel. Most will be suprized to find that it's only about 5%. Just run those engines.

Eric Henning
 
" What don't you guys like about running your engines 75%"

75% of what? Sales brochure literature ?

Run a gas engine at 75% and by by service life .

Happily the usual Ford Econo-Power conversion is RATED 120HP , but in reality is about 80 Hp engine for long duty .So at 2-4gph lives long and prospers.

The NEW electronic high pressure injection diesels can get away with light loads , at least for the operation in a trawler for a decade.

The folks with the BIG problem have the oxymoron "Fast Trawlers" that may see 15K or 18K at flank, thanks to a 330hp industrial push , and then attempt to cruise at SL 1.15 for efficiency .

For them selling the 330HP unit and getting perhaps a 100hp industrial engine would work.

IF the 330hp is not industrial just a car engine transplant (Yannmar/BMW) style , the engine will only produce gas car engine service life 2000hrs to rebuild.

So the swop can be done fairly early if the boat is used at all.

Visiting Canada doing the mud run (aka great loop) much of the system is limited to 10K,,,, thats Klicks , or 5K , 6 Statute.

Thats a real bear for most so the few places the boat can get an hour at 80 or 90% rpm is a blessing!

FF
 
nomadwilly wrote:

What don't you guys like about running your engines 75% ? Don't give me this hogwash about being too old and or being not designed for it.
Eric---

Here's the thing.* If we were talking about new engines, by which I mean a new entry into the marinized diesel world,* there would be some merit perhaps in speculating about how hard to run them because the engines would have relatively short histories to go by.

But in the case of the FL120, it is meaningless to talk about what percent of power would be best for it because this is an engine with a 40 year history of powering boats.* People have run them for thousands and thousands*of hours in the 1500 to 1800 rpm range.* And in this service, these engines are considered 12,000 to 14,000 hour engines.* This isn't speculation.* This is what's happened over the last 40 years.* Some of them in commercial marine service have gone in excess of 25,000 hours before needing an overhaul (according to Bob Smith & Co. at American Diesel).

So why follow some armchair theory with these engine when 40 years of history proves conclusively that running it year after year after year at low power settings results in a longer service life than any boater will most likely ever need?* Assuming proper maintenance and no operational abuse of course.*

So my question isn't why don't we run them at 75% power, it's why should we?* Forty years of reliable, long-lived service is definitive proof that there is no reason whatsoever to run these engine at higher power settings if we don't' want to.* Running at low power settings with whatever the oil temperature happens to be has resulted in thousands upon thousands of reliable engine hours in a huge number of boats all over the world, from warm waters like the Mediterranean to the cold waters of the PNW, Canada, and the UK.* People like D'Antonio can theorize all they want about what is best for an engine and installing*oil warmers and whatever, but in the case of the FL120 at least, these theories are simply armchair excercises when compared to the actual service history of the engine.

This is not necessarily the case with*newer types of engines since they don't have 40 years of operational history from all corners of the globe as proof of what works and what doesn't.

*
 
OK.. I'll stick my neck out here a bit. There must be 500 guys on this forum and at least 100 w old Ford 120s. Many must have run them for 10 years at 1600rpm or less. I've seen many for sale ads for GB 32s claiming less than 1.5 gph. If guys like that are running them at 25% load for 10 years and still have good compression, only trace smoke at start up with good starting performance, no stuck rings and no glazed cylinder walls* ..* If that can be truthfully said I'd have to hang up my light loading rant but there are sooo many guys here that like to run way light and think it's way cool that there would probably be some that would belly up to the bar w half truths or worse. I think there is only one source of information that would objectively settle this issue and that is the manufacturrers. Not marinizers* ..* they are just salesmen and mechanics. We need engineers w specific knowlege and experience. Notice that this excludes Mr. DeAntonio.* I still say a boat should have the correct amount of power and run at 60 to 80 % load. I would think all the problems associated w light loading could be solved w the right combination of piston,rings and cylinder wall finish and material. Perhaps soft rings and chrome cylinder walls would be amune to loading abuse.

Eric Henning
 
nomadwilly wrote:

If guys like that are running them at 25% load for 10 years and still have good compression, only trace smoke at start up with good starting performance, no stuck rings and no glazed cylinder walls .. If that can be truthfully said I'd have to hang up my light loading rant
I have no quarrel with your statement that a lot of boats, including ours, would get along just fine with smaller engines.*

But we fit your description to a "T."* We bought the boat in July, 1998, started running it up here in the PNW in August 1998, and we always cruise at 1600 rpm (or thereabouts, the SW tach accuracy is nothing to write home about).* The engines emit no more light blue smoke at startup than they did ten years ago,* they clean up within about two minutes of starting, same as in 1998, and the engines start within a second of hitting the start buttons, same as in 1998 (I've timed it just out of curiosity) even in the winter when the engine room heater keeps the engine room at about 50 degrees.* This isn't just me saying this--- the very experienced marine engine expert and friend who accompanied us to California in 1998 to check out the boat commented then on how fast the exhausts cleaned up after start, and he was on the boat last fall and commented that they still cleaned up just as fast.

Each engine uses less than one quart of oil every 100 hours (the starboard engine leaks most of its quart out because I'm too lazy to climb around back of the engine and put on a new fuel pump gasket).* The fuel consumption is the same today as it was in 1998 so far as I can tell.

I can't tell you about the condition of the cylinder walls because I'm not going to tear the engine down to find out (if it ain't broke, don't fix it).* And from talking to friends who have the same kind of engines in their boats, some of whom have owned their boats longer than we have, our experience is not the exception.

This isn't to say that the engines won't explode the next time we start them.* But in the past ten-plus years of running the boat, we have noticed no change whatsoever in the performance of the engines.* And we use the boat year round, although we tend to take lots of shorter trips (5-8 hours of running each time) and only one longer trip per year, like two weeks to Desolation Sound, as opposed to retired folks who might take several longer trips a year.* But in all the years we've owned the boat I doubt it's ever sat more than three weeks without being run other than last December and this past February when I was in China for the whole of each month.
 
Gee Vinny I wish I knew ya when I ran a 54 1500N coupe.

It was so slow (60's in the 1/4) that I finally flopped the ring gear and stuffed in a Corvair with a Thomas 4 carb kit.

1/4 times in the low 90's and the mileage only dropped from 35 to 29 , a worthwhile exchange to be able to shoe the rear grill to an E- Jag , the Navy student pilots dream machine in '65 or so.
 
Vinny wrote:

Don't you wish you had that 356 1500 with the original engine in*it now? $$$$$
A good friend of mine had a 1954 Corvette while he was in college in the 60s.* He sold it for a song because back then, it was just a used car.* No big deal about it.* He is still kicking himself for not keeping it.

Contrast this to a co-worker of mine*who in 1956 bought a used (only one month old) Fender Telecaster guitar for about $300 (a lot of money back then).* He was recently offered $30,000 for it.

We've all had and then sold stuff we now wish we'd held onto.* In 1966 I bought a National Match M-1 Garand in a gun store in Ft. Collins, Colorado for $65.* It was in mint condition.* (For anyone who doesn't know, the National Match version of the M-1 Garand had better machining, closer tolerances, and better sights for 1,000 yard target shooting).* After my freshman*year at Colorado State University I moved back to Hawaii to finish college there.* Rather than deal with the hassle of getting the rifle back to Hawaii and facing a mother who didn't like guns much, I sold it back to the same store I bought it from for the same $65.* What a dumba*s thing to do...
 
OK, so this appears to be another one of Foster's follies.

Ran for about an hour with both engines at about 1400 (I say "about" because the engines were in sync by ear, but the four tachs read 1500-1425-1350-1300).* Shot the oil pans with the IR and both were in the high 150s.* In a perfect world, I'd like to see 20 degrees hotter... but certainly a good deal warmer than I had worried would be the case.

On aircraft, the rule of thumb that I learned in A&P school was that around 170-180 degrees in the sump, oil that ran through the lifters and then down into the rockers and around the valves would briefly heat to 220 or so - hot enough to boil off any moisture that accumulated.*

On a side note, I was pleasantly surprised to see that the port engine water temperature came up to 160 instead of its usual 120-130.* Didn't make any sense since all I had been working on was raw water plumbing and the raw water flow was now significantly improved - but if the run temp was a bit warmer, so much the better.

Unfortunately, over the next 20 minutes, it crept up to 180 and then 200.* Smelled a bit warm & steamy, so I shut down the port engine for the next hour or so and fired it up for maneuvering and docking.* After I docked, found a dry expansion tank and a green bilge - apparently when I climbed around the front of the port engine to get to the raw water side of the engine, I managed to lean on one of the hot water hoses that leads to the heat exhanger in the water heater... and put a bit of a tear in it.*

Maybe it's time to stop reading the Homer Simpson Marine Mechanics' manual, eh?

D'oh!
 
I'll take an E Type Jag any day. In 1967 I sold a Colt 1911 45cal for 30 bucks; my M1 Carbine went for about $50.
 
Marin,
I think you must cruise at about 8 knots. How fast would you cruise if you had two 250 hp engines ? Would you run them 45% like your Fords ? What if you had two 50 hp engines. Would you run them at 45% ? Why do you go as fast as you go ?. If I ran my Willy at 45% I'd probably make 5 knots and burn .4 to .5 gph. I could run (at that speed) from Bellingham to Thorne Bay on one tank of fuel if I did not stop at night. I run 2300 rpm most of the time (3000 rpm engine). Your GB dosn't* benefit as much as my FD from slowing down. However, with a FD hull I don't have as wide a range of speeds to travel. The propper, correct, prudent and sensible speed to travel is a very narrow range. Your'e SD or SP hull has a much wider range of practical speeds to travel but it's still a narrow range. People that buy semi planing boats that intend to run them most all the time at 30 to 50% almost universally think they need lots of extra power if a storm blows up or whatever. Walt buys into that and many others I'm sure. I think it's a carryover from autos. With cars we are accoustomed to having lots and lots of extra power and when we get a boat we don't feel secure whithout lots of extra power. The latest 30' Willards were powered w a 55 hp engine* ..* way too much power. The manufacturer claims "marketing reasons" when asked "why so much power".
Sounds like your engines are doing fine Marin. Given the history you presented (and I do belive you) they should last a long time yet. I'll bet you do all the right maint things and do proper warm ups and cool downs. I'd still like to hear what the manufactures say. The manuals say "avoid this and that" but no mention of engine loading. You'd think if it were a big deal they would say so. I still say 60% should be the minimum but I'll not rag on you guys for putzin around.

All Ahead 1/3
Eric Henning
 
nomadwilly wrote:

Marin,
I think you must cruise at about 8 knots. How fast would you cruise if you had two 250 hp engines ?
Yes, 1600 rpm gets us about 8 knots. We had the props pitched down last year so we get a little less speed for a given rpm now but the fuel consumption went down a bit as did the engine loading (as indicated by the EGT gauges). So it's pretty much a wash in terms of benefits but at least the props are balanced and shaped correctly now and the engines can reach their rated WOT rpm, not that we'll ever run them that fast.

If I recall correctly, the speed of our boat is just a tad under 8 knots according to the formula. The engines achieve full operating temperature at about 1300 or 1400 rpm under load. So 1600 rpm and 8 knots seems to be the sweet spot where engine temp requirements are met, the speed through the water is acceptable, and the fuel consumption is reasonable.

If we had a pair of 250 hp engines we'd look for the same sweet spot although the engines would most likely be turbocharged so they'd probably have to be run harder to keep the temperatures where they should be. Which would force us to burn more fuel. But maybe we'd be cruising at 9 or 9-1/2 knots. So I wouldn't mind a pair of 250 hp engines if they were designed to be run at 40-50 percent power with no bad side effects because I'd rather cruise at 9-1/2 knots instead of 8 knots given a reasonable fuel consumption.

However I would not want a pair of 40 or 50 hp engines engines that were working hard to move the boat at hull speed or less.

This is the challenge my friend Carey faces with his single engine lobsterboat with a 420 hp turbocharged engine. The boat is intended to be run at about 15 knots. Which he used to do until fuel prices started to climb. So now he walks the tightrope between maintaining sufficient engine temperature and keeping his fuel consumption as low as possible. These days he cruises a bit faster than we do, maybe 8-1/2 to 9 knots or so, although he does open it up for part of every run to keep the injectors from loading up.

I'm a big fan of speed. If boat, engine and fuel costs were no object, I'd prefer a 15-20 knot boat. But our boating budget wouldn't accommodate that kind of boat ten years ago so we have a slow-poke. But if I can't have 15 knots I can at least have 8. I've got no interest in cruising at 6 knots or less in any kind of boat no matter how low the fuel consumption is. I enjoy a journey as much or more than the destination, but I don't want the journey to become interminable, particularly with our currents up here. Given the twisting courses we usually have to follow through the islands, we almost never get the benefit of a favorable current through a whole journey. We may be zipping along at 11 or 12 knots SOG down Bellingham Channel on a big tide day, but then we'll turn a corner and be going against that same current and we're down to 4 or 5 knots SOG. So you can't really use the currents to help speed up a journey in a 6-knot boat because they'll be slowing you down as often as they'll be speeding you up. The only practical solution in these waters is a faster boat.




-- Edited by Marin on Saturday 9th of May 2009 01:58:23 AM
 
Date: 14h, 13m ago


Don't you wish you had that 356 1500 with the original engine in*it now? $$$$$


NO,, I wish I had held on to the MB 300SL Roadster , I sold (furlough) for $2600 back in 1971 .

No problem tho with the Weymar inflation that will happen after Dumbo monitizes 5 TRILLION more debt , our TOAD a 1980 VW Diesel Rabbit will be "worth" (fiat currency) aT LEAST $100k , AFTER ALL HOUSE FUEL WONT HAVE THE $12.00GAL* ROAD tAX.
 
Marin Wrote: "I'm a big fan of speed. If boat, engine and fuel costs were no object, I'd prefer a 15-20 knot boat. But our boating budget wouldn't accommodate that kind of boat ten years ago so we have a slow-poke. But if I can't have 15 knots I can at least have 8. I've got no interest in cruising at 6 knots or less in any kind of boat no matter how low the fuel consumption is. I enjoy a journey as much or more than the destination, but I don't want the journey to become interminable, particularly with our currents up here. Given the twisting courses we usually have to follow through the islands, we almost never get the benefit of a favorable current through a whole journey. We may be zipping along at 11 or 12 knots SOG down Bellingham Channel on a big tide day, but then we'll turn a corner and be going against that same current and we're down to 4 or 5 knots SOG. So you can't really use the currents to help speed up a journey in a 6-knot boat because they'll be slowing you down as often as they'll be speeding you up. The only practical solution in these waters is a faster boat."

This sums up my "preference" for a PNW Boat! Well said Marin...I'm kinda sick of hearing about 1.5 gph, 6.5 kts, etc. My god! I don't want to sit at anchor waiting for a slack tide or one going my way! (Now,* for the "flack".)
 
Marin,
I would run your boat 10 knots IF fuel cost was not an issue. I think fuel costs are driving this under loading issue. Guys are running their boats real slow to save fuel and want real bad to be able to feel good about it so when somone like me or Steve D comes along and says they are doing something wrong I/we get covered w tomatoes. Thats OK on the Trawler Forum as it's not too messy. I remember the Albin club where almost everyone thought it was sinful to go over 6 knots and 90 % of the boats were capable of 10 knots and sustained speeds of 9 knots. Never did figure out why going so slow was so appealling to them. I ran 8.5 knots w that boat but later I went to Alaska and back at 7.5 knots. I'm with you in that I like high semi-planing speeds** .. 12 or 13 knots would be super but I need to feel comfortable in Dixion Entrance and I need that 1 gallon per hour as there are great distances to go up here. If I had lots of money a 31' (1960s) Bertram would be in my slip. You talk about "full operating tempeture" and I have a feeling you mean coolant. The coolant reaches operating tempeture long long before the engine is heat soaked. I remember my Albin after a 4 hr run there were lots of things (like the gearbox) that were much hotter than if I had been out for only 30 min. But then the engine load you cruise at is part of my warm up. But then if I had your boat I'd be running it even slower w modifications like removing the oil cooler, running extra high detergent oil ect ect. I'm poor** ..* can't even afford 6 gph. But I can afford my Willard and I've got the time.

Eric Henning
 
Hey Slo,
I've got Jaguar in my blood too. In 1969 I had a XK 140 MC roadster, black w red brake drums, wire wheels and red leather inside. This was an open cockpit roadster w leather padding all around the "hole". The top was like a tent. It didn't power down like a convertible* .. you took it down like a tent, folded it up like a tent and stowed it in the trunk. That Jaguar was the best car for picking up chicks EVER. Several times while stopped at a light girls just hoped over the door and plunked right down on the seat. Of course it was a small college town and I was a lot better looking in 1969. My best friend had a 300SL Gull Wing and it was amazing how the two cars almost were a perfect match on paper but TOTALLY different to drive. The SL was a dog to drive but it did wonderful things. You needed both hands on the wheel around a corner (the steering was that heavy). No shifting in the corner. The Jaguar was unpredicable in* hard corrnering when pushed** .. not good but a total sweethart when cornnering as hard as a Mustang at it's raggard edge. The 140 MC had a brass plaque on the dash claiming it to be an exact replica of a 140 that went 149mph for 24 hours on a race track. What a joy that car would be today but it would have an awful chain around my neck for all these decades** .. not to mention the expense.
Walt
There are lots of boats that give great joy to thier owners that never exceed 7 knots. So far I've not sat at anchor waiting for a tide change (or at dockside). Iv'e been slowed to a bit under 4 knots and don't consider it a big problem* ..* "My God" whats YOUR problem Walt. By the way * ..* I burn almost half of 1.5 gph.

Eric Henning
 
Eric: You can take the hook out of your mouth now...you came through like a champ!<grin>
 
I burn almost half of 1.5 gph.

.75 GPH is perhaps 13 hp fine for a 25-30ft LWL in about a 6-10 ton displacement boat , at 6 maybe 6.5K (good designer , clean hull, right prop.)

FF
 
Another short story: in 1983, height of the oil boom in Houston, I decided to look for an E-type. Found some dogs in the want ads and passed. Then went to this Jag repair shop on Kirby Drive, just so happened that it was owned by one of my upper classmen from Texas A&M. Told him what I wanted to do, and he asked what I planned to do w/ the car. Why, drive it every day, take it on road trips for business, etc. His advice was " then you need to buy two cars cause the Jag will spend about half its time and a lot of your money here in my shop". Thank goodness for the Texas Aggie brotherhood, I ended up buying a Datsun 280 Z, hell of a car, 12,000 brand new. Drove it for a couple years and sold it for 8700. Wish I still had that one, it would fly.
Mike
Baton Rouge
 
Yea yea Walt* ..* if I did'nt know I was being baited I would prolly be pissed. A man w any hair on his chest can't let an apparent insult go unchallenged. I may mention those dreadful low numbers again* .. even soon. I could put you on hold* .. what kind of music would you like?
Sloboat, The Es are very hot in warm weather and they have less foot room than a Triumph Spitfire and the gearbox is old school but after that** ..* FANTASTIC car. Five gph at over 8 knots for a boat as big as yours seems like really good efficiency. Is it a Cummins ? Walt does real well w his as I recall. Ganged engines! That sounds really interesting. Have you seen the write up on single engines w twin screws, PMM Feb 05 P 112 ? All done w gears. I think the kind of chain you're talking about requires a box w oil like an old Harley and probably a tensioning shoe of plastic. Are you prepared for an over the counter system or are you thinking of a home grown effort ?
FF, 16000lbs disp, 37hp at about 60% load (22hp) running 2300rpm on a 3000rpm engine w a BW gear w 2.57-1 ratio. and a 18X14 wheel. Burn rate .85gph. Indeed your'e very close* .. oh* .. 6.15 knots. Don't tell Walter we were talking about such rediculus numbers. You may not belive it but at a 75% (28hp) load I can achieve a speed in excess of 6.5 knots. I don't live in fear of 6 or 7 dollar a gallon fuel but* getting to the next port or anchorage before dark can be a problem. Actually it's a rather rare occurance.

Eric Henning
 
Eric...touche!!* I hope you know I was not denigrating 6.5 kt boats as I can see the logic as well as the economy on such vessels.

All I was trying to say (as well as pull your chain) was that Marin's treatice on cruising boats pretty much coincides with my own thinking. I think that 6-9 kts is a relaxing speed to cruise at. There are times, however, that 20 kts comes in real handy, gph be damned. With that in mind, the GB 41 seems to fit my desires quite well but the jury is still out on the pod thing.

For those subscribers that took my "slow boat" remarks seriously, I offer my sincere apologies. We all can't have a speed demon like mine. (8.5 kts)
 

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..there are some very interesting silent chain drive designs used in Navy patrol boat research to "link" four engines to twin shafts....no reason they wouldn't work in the opposite direction.

Those gear boxes have SAE 1 so are EZ to use.

I figure a 4 cyl imitation John Deere , as the slow side ,

and series 50 DD on the fast side .

60-75 hp slow, 250-330hp (reliable truck numbers 24/7) on the defuler side.

ZOOOOM!
 
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