How much engine do I really need?

[OldDan1943]

Yup all gauges in the 40 to 60 % range and all is perfect.

This is true with your car too.

 

[DavidM]

David and Ski, doesn't the Cummins(6 series) have a coolant cooled oil cooler? Does that help in what we are talking about? When everything gets up to 180 degrees I would think that would help. My little 4LH Yanmar had a seawater cooled oil cooler. I had a bitch of a time changing oil on that thing because I could never get the oil temp up to help the oil flow. That would not have been good to run that engine slowly all the time.

Yes, I believe the Cummins does have a coolant cooled oil cooler. My Yanmar 6LY has a sea water oil cooler but it will fully warm up to operating temps while just making 50 hp at 1,600 rpm, which gives my 7 kt typical cruising speed. But the oil is probably cooler than on the Cummins.

Some engines I believe even have thermostatically controlled oil coolers. Don't know which.

David

 

[Cooper]

Not to ruffle any feathers , or get kicked off the Trawler forum , but has anyone ever heard of someone really loading up a trawler with a semi displacement hull with a lot of horse power ? I mean to really get it up and over . I have a 1979 ms 34 . This boat is new to me but have run many commercial fishing boats with almost the same hull (why I bought the 34 )and by not being speed demons ,we usually get up easy to 18 to 19 with a 380 hp with boat balanced correctly . Yes ,I am enjoying going slower and yes, I enjoy the fuel economy and no, I am not repowering . Just wondering if anyone did it and what was the result?

 

[Sealife]

Little rusty, but I believe it has been done with that hull. Maybe it was Jay Leonard had a 270 cummins. I remember something about 20-21kts it became a bit squirrelly.

Been years, but I had same hull and remember doing the research. It was on the old mainship yahoogroups.

 

[sunchaser]

Ski and David

Can only but agree with your posts 26 and 27. I'd add my confusion as to why Sinter states a marine after cooler increases the chances of glazing. Cooing the charge air would seem a positive in improving engine performance whether NA or Turbo with after cooler.

Todays common rail diesels do a very good job of controlling fuel under light load conditions. To the point sport fishing boats can fish for hours on end at near idle. Possibly Sinter wrote his comments a few decades ago.

And as Baker says, the coolant cooled oil coolers work well in keeping oil up to temperature under light loads. No mention by Sinter as to keeping oil temps up in the + 180F range.

 

[AusCan]

Let's face it, most folks buy used boats and live with the engine that came with it.
Repowering? We all home to sell the boat before that happens.

Actually - When I bought my boat I knew the original raw water cooled 36 hp Volvo may not last long, but the boat was what I wanted and the price was right. The engine overheated if I pushed it hard, was a bit smokey, parts were hard to find, and I never felt I could trust it completely. Especially here where there is no tow service, and I don't see another boat all day.

A year later, I wasn't upset when I checked the dipstick and found it frothy white. I didn't even investigate the problem. For less than 16K I was able to replace the engine & gearbox and replace my fuel tanks while the engine was out. Now I have a boat I can trust 100%.

 

[RCook]

Ski and David

Can only but agree with your posts 26 and 27. I'd add my confusion as to why Sinter states a marine after cooler increases the chances of glazing. Cooing the charge air would seem a positive in improving engine performance whether NA or Turbo with after cooler.

Todays common rail diesels do a very good job of controlling fuel under light load conditions. To the point sport fishing boats can fish for hours on end at near idle. Possibly Sinter wrote his comments a few decades ago.

And as Baker says, the coolant cooled oil coolers work well in keeping oil up to temperature under light loads. No mention by Sinter as to keeping oil temps up in the + 180F range.

Anecdotal example: our 26-footer's 1998 260hp Volvo KAD44P diesel.

Not common rail, but an early electronic engine. Turbocharged, supercharged, clearly a #8 in Bob Sinter's scale.

It has 6502 hours on it so far. After cruising at mostly at 3000-3400 RPM for its first two years, we've run for the last 4500-5000 hours at 1300-1400 RPM, 6-7 knots, more than 95% of the time, putting out ~30 hp? Running just hard enough to keep temps up to 175-180. Runs as well as when first broken in, burns no more oil, smokes no more, shows no sign of deterioration, oil analysis fine, etc.

 

[Gordon J]

Wouldn’t have mattered

Did he have trim tabs ?

I have twin, is 330s on the by Ocean Alexander 456, and loaded for a winter in the Bahamas which means cases of wine beer Gin, etc we can only get 11 or 12 kn out of our boat. Empty, she will do 15.

Perhaps if I threw the head of lettuce overboard we could make more speed.

 

[OldDan1943]

I have twin, is 330s on the by Ocean Alexander 456, and loaded for a winter in the Bahamas which means cases of wine beer Gin, etc we can only get 11 or 12 kn out of our boat. Empty, she will do 15.

Perhaps if I threw the head of lettuce overboard we could make more speed.

Tuffy question, Got a water maker on board? reduce the FW by half or more.

What are you doing with lettuce on board?

 

[Nomad Willy]

Sunchaser wrote;
“And as Baker says, the coolant cooled oil coolers work well in keeping oil up to temperature under light loads. No mention by Sinter as to keeping oil temps up in the + 180F range.”

IMO if the lube oil temp is kept up to 180 and a heavy load is put on the engine every several hours for a few minutes one should be good to go.

BUT I seriously question if an engine coolant will keep the lube oil up to 180. That little cooler is going to replace the heat of a big fairly hard working engine? ..... but if it can ......
Perhaps it’s a solution to the underloading issue. I’m still glad I can run my engine at 50% load w/o too much fuel burn and w/o too much noise.

 

[psneeld]

Not to ruffle any feathers , or get kicked off the Trawler forum , but has anyone ever heard of someone really loading up a trawler with a semi displacement hull with a lot of horse power ? I mean to really get it up and over . I have a 1979 ms 34 . This boat is new to me but have run many commercial fishing boats with almost the same hull (why I bought the 34 )and by not being speed demons ,we usually get up easy to 18 to 19 with a 380 hp with boat balanced correctly . Yes ,I am enjoying going slower and yes, I enjoy the fuel economy and no, I am not repowering . Just wondering if anyone did it and what was the result?

My style hull had from 120 hp to over 200....sorry foget if it was a 250 Cummins or what from the factory.

I run it at about 45 ho to get 6.3 knots. Anything more and the wake grows exponentially as the wayetline length is 34 feet.

The brochures say with the added hp, the boat cruises at something like 14 knots.

I have run quite a few boats and I cant imagine this hull doing 14 knots...oh I belisve it was done...but then again I lived in the F-4 Phantom fighter jet era too.

 

[Bill & Stella]

On a trawler, the vibration of a four cyl may push the choice to the smoother six. But there are not many low hp sixes out there unless you go to an obscure brand which creates its own problems.

So sometimes all things considered, the best (least bad) choice is to go with a larger engine in the trawler. The Deere 4cyl have balance shafts, so that that can be a good option.

I install lots of engines. The John Deere 4045's and IVECO NEF 100's have counter rotating balance shafts, and are very smooth. Lehman 90's, Cummins four's, Kabota based four's, and many others, do not, and they all shake. The Cummins four is the king of shakers!

Since JD stopped making the 80 HP natural I used the BETA 85. Its Tier III and 1/2 the current price of the smallest JD 4045.

http://betamarine.co.uk/portfolio-item/beta-85/

I have solved the shaking problem since 1980 with three point suspension. I'd like to show a picture of a BETA installed yesterday. However, since PhotoBucket and DropBox have eliminated the direct photo link I'm not sure how to post photos on this site.

 

[North Baltic sea]

Hi,


Almost always only about 50 hp, but sometimes it is necessary to harness horses more abundantly prop curve look about 250 hp. Speed about 7 / 15 knots.


NT37 + Cummins qsb 5.9 380hp.


NBs

 

[Baker]

Sunchaser wrote;
“And as Baker says, the coolant cooled oil coolers work well in keeping oil up to temperature under light loads. No mention by Sinter as to keeping oil temps up in the + 180F range.”

IMO if the lube oil temp is kept up to 180 and a heavy load is put on the engine every several hours for a few minutes one should be good to go.

BUT I seriously question if an engine coolant will keep the lube oil up to 180. That little cooler is going to replace the heat of a big fairly hard working engine? ..... but if it can ......
Perhaps it’s a solution to the underloading issue. I’m still glad I can run my engine at 50% load w/o too much fuel burn and w/o too much noise.

Eric....the coolant "cooled" oil is a good thing. In the Cummins it always comes up to temp and the oil comes up right along with it. In the Yanmar, the disparity was shocking.....the coolant could be 180 and the oil temp could be almost cool to the touch.

 

[Irish Rambler]

First, it depends where you want to cruise.
Second, it depends on what time you have available.
Third, is how deep your pockets are.
Fourth, is the admirals comfort.

First, where you want to cruise determines your hull shape.
Second, If you want to dash to the furthest marine and back in time for work Monday morning you'll need two big engines burning 10/12 gallons an hour
Third, see number two.
Fourth, if the admiral doesn't like your marine lifestyle, either the boat goes, or she goes.
The only difference is time.

In my case I have an 80hp Perkins 4236 N/A running easy at 1950 rpm driving a 42 ft. low wash displacement boat, it just chugs along at 7.5 knots (with occasional 10 min bursts to WOT to discourage bore glazing) forever, despite the admiral loading it to the max.
The tides are my department and we've often had 12 knots on the log for 3/4 hours.

 

[North Baltic sea]

Not to ruffle any feathers , or get kicked off the Trawler forum , but has anyone ever heard of someone really loading up a trawler with a semi displacement hull with a lot of horse power ? I mean to really get it up and over . I have a 1979 ms 34 . This boat is new to me but have run many commercial fishing boats with almost the same hull (why I bought the 34 )and by not being speed demons ,we usually get up easy to 18 to 19 with a 380 hp with boat balanced correctly . Yes ,I am enjoying going slower and yes, I enjoy the fuel economy and no, I am not repowering . Just wondering if anyone did it and what was the result?

Hi,
When I applied my NT home on the other side of the Baltic Sea, the trip was about 550-600nm and drove all the way to 15 knots, except for 3 refueling and doging boat anchorage or marinas for 3 nights.

After that, sometimes when the unlucky wave follows the quarter. The boat works brilliantly at this speed and the throttle is in accordance with Cummins, no problem, other than money burns and returns to the sky, but for all it does not broblems, Unfortunately for me .

If you want to drive quickly often, the better choice would be planig Hull which is very stable to drive at SD speed in a really rough ocean and in a suitable wave of planig ups + 22-knots and some times cruising "trawler" speed when sea is gentle..

NBs

 

[Adagio43]

EGT? Is that exhaust gas temperature?

 

[BandB]

Wifey B: 5000.

 

[Baker]

EGT? Is that exhaust gas temperature?

Yes

 

[Rebel112r]

Lugger Bob, last name is Senter!

Guest Interviews-Guest Interview – Bob Senter (Lugger Bob)

 

[FlyWright]

Not to ruffle any feathers , or get kicked off the Trawler forum , but has anyone ever heard of someone really loading up a trawler with a semi displacement hull with a lot of horse power ? I mean to really get it up and over . I have a 1979 ms 34 . This boat is new to me but have run many commercial fishing boats with almost the same hull (why I bought the 34 )and by not being speed demons ,we usually get up easy to 18 to 19 with a 380 hp with boat balanced correctly . Yes ,I am enjoying going slower and yes, I enjoy the fuel economy and no, I am not repowering . Just wondering if anyone did it and what was the result?

The 34 Californian had been powered with everything from twin 85hp Perkins 4.236s to Detroit 250s like chc's. My cruise with twin 4.236s is 7.5K and WOT 10K. Chc's WOT is 23K! It's quite a ride but the bow is so high that the lower helm visibility is restricted. At those speeds, it's a FB-run boat only.

I think the sweetspot with this hull would be the 200-210 Perkins 6.354 or Cat 3208 for about a 12-14 kt speed. More ER room with the big Perkins though.

And as Baker says, the coolant cooled oil coolers work well in keeping oil up to temperature under light loads. No mention by Sinter as to keeping oil temps up in the + 180F range.

Eric....the coolant "cooled" oil is a good thing. In the Cummins it always comes up to temp and the oil comes up right along with it. In the Yanmar, the disparity was shocking.....the coolant could be 180 and the oil temp could be almost cool to the touch.

My Perkins 4.236s run at about 165*F oil temp. They've been described to me as "over cooled", but they do not seem to suffer from the 'neglect'. On this engine, it appears to have no negative effect.

Last summer my port oil cooler sprung a leak on a long trip so I had to bypass it for about 10 hrs of operation. The temps rose to and stayed at 240*F without the oil cooler connected. I was impressed. (Yes, I changed the oil when we returned and replaced the cooler stack.)

 

[FF]

"My Perkins 4.236s run at about 165*F oil temp."

ALL engines have blowby , which puts combustion byproducts into the engine lube oil.

Warmer oil temperatures will evaporate these fluids faster.

There is usually enough produced that folks , looking on a dipstick, think there engine burns NO oil.

Modern diesel oil is about 20% additives , mostly to help with EGR contamination.

IF your oil is changed frequently enough the additives will get the acid in the blow by .

 

[Lady In Blue]

my addition may be pointless. I understand your concerns about too much engine.

I,m in that boat also.

Too much engine for my 32'er. My engine now is old (40yrs) v555 cummins @217 hp, yet it has done fine at 7 -8k. For the last 30 years. Originally powered to plane but cannot because we carry too much, er, stuff.

If you buy a boat with what you consider to be too much hp it doesn't mean it has to be used. Yes run it up for 10-15 minutes once daily on a long run to clean it up if concerned.

Not wot. Not needed. Just bring it up to a point where it is working harder on a slow plane or just on to the lower portion of the hump.

For a good normal cruise speed stay just below,10-15%, the hump speed , and it will be loaded sufficiently to be fully at operating temps which is what is important. That has also "derated" the engine.


As pointed out you will have a tad more mtc. With a seawater cooled after cooler but not that big deal unless ignored.


Stop worrying so much about the engine hp unless you are in the position to spec. Exactly what you want or do a repower. Just learn to run and maintain it smartly and whatever you have will serve well.

I strongly suggest you add one of the most important guages, egt. It will tell you ,with some experience, just how hard you are operation g the engine, overloading or easily.

Jmo.

egt?

 

[High Wire]

egt?

Exhaust Gas Temperature

 

[C lectric]

Yes, EGT is exhaust gas temperature.

Unfortunately usually not installed by builders but one of the most important guages on the boat especially if you want the engine to have a long life.

 

[Sharpseadog]

Engine Power

I have a 2007 Mariner Seville Pilot House 37 (Helmsman 38) which I bought in 2015. The PO had the Cummins QSB 5.9 re-programmed from 220 HP to 380 HP. He also has Bennett trim tabs. I guess he thought he might get her up on a plane, but at 40,000 lbs. fully loaded, no way was she ever going to plane. I can cruise at 7-8 knots on 3 GPM , but if I firewall it, I only get up to about 11-12 Knots but I am burning 17 GPM . I have had very few occasions where I pushed it that hard, other than to "blow it out" now and then. We do have some very strong tidal currents in my area, especially going through narrow passages against max flood/ebb, and actually needed the extra power, but I'm pretty sure boat would have been fine with the 220 HP configuration. Does anyone want to buy a set of used Bennett trim tabs? Or can anyone explain what possible good they are on an 8 Kt boat?

 

[gaston]

I have a 2007 Mariner Seville Pilot House 37 (Helmsman 38) which I bought in 2015. The PO had the Cummins QSB 5.9 re-programmed from 220 HP to 380 HP. He also has Bennett trim tabs. I guess he thought he might get her up on a plane, but at 40,000 lbs. fully loaded, no way was she ever going to plane. I can cruise at 7-8 knots on 3 GPM , but if I firewall it, I only get up to about 11-12 Knots but I am burning 17 GPM . I have had very few occasions where I pushed it that hard, other than to "blow it out" now and then. We do have some very strong tidal currents in my area, especially going through narrow passages against max flood/ebb, and actually needed the extra power, but I'm pretty sure boat would have been fine with the 220 HP configuration. Does anyone want to buy a set of used Bennett trim tabs? Or can anyone explain what possible good they are on an 8 Kt boat?

Leave the trim tabs on it would cost more to remove them and fill the holes than the second hand market.They also look good on the inventory list when you sell the boat

 

[Fletcher500]

Sharpseadog: My days of working on engines ended a long time ago, so I generally stay out of these discussions, but I was wondering about a few things you have posted.

You noted:

"The PO had the Cummins QSB 5.9 re-programmed from 220 HP to 380 HP." I have never heard of anyone doing this. So he upgraded the turbo and coolers as well? I would assume this is a fairly extensive project and not just some programming.

" I guess he thought he might get her up on a plane, but at 40,000 lbs. fully loaded, no way was she ever going to plane." I don't think anyone who buys this boat expects to be on plane. The builder and many others like the 380 to get in the semi/displacement mode for some extra speed if they need it.

"But I'm pretty sure boat would have been fine with the 220 HP configuration." I think the builder would also agree with this. 250 is the standard power package, but many decide to upgrade. It could also help on resale.

"Can anyone explain what possible good they are on an 8 Kt boat? " I don't know either. No trim tabs on the new 43 that I ordered.

 

[C lectric]

I've posted this before but here goes again.
I used to think the T.T. were pointless on my boat but it came with them so I did not have a choice. They were there.
Most of our boats are semi displacement/semi planing hulls.
The T.T. can take a list out of the boat attitude while running.
The T.T. can actually reduce a big rolling stern wave, by lifting the stern a bit, if you are pushing the hull speed a bit.
I can actually hear the engine unload a bit from no tab to full tab.
The biggest difference comes with full tanks.
When the boat has burned off a bunch of fuel and we have used a bunch of water I back the tabs off since I do not want to push the bow down.
Of course in heavy following water they are fully backed off.
Sometimes in heavy head water they are backed off as I want the bow to lift that bit sooner and more readily.

My tabs are really too small to make a big difference but a difference they do make.
I found mine make the most noticeable difference when the boat is heavily loaded for a trip.

If you have them try them. You may find they are of more use than you realize. If you really find they don't make ANY difference then just back them off.

 

[boatpoker]

Sharpseadog: My days of working on engines ended a long time ago, so I generally stay out of these discussions, but I was wondering about a few things you have posted.

You noted:

"The PO had the Cummins QSB 5.9 re-programmed from 220 HP to 380 HP." I have never heard of anyone doing this. So he upgraded the turbo and coolers as well? I would assume this is a fairly extensive project and not just some programming.

" I guess he thought he might get her up on a plane, but at 40,000 lbs. fully loaded, no way was she ever going to plane." I don't think anyone who buys this boat expects to be on plane. The builder and many others like the 380 to get in the semi/displacement mode for some extra speed if they need it.

"But I'm pretty sure boat would have been fine with the 220 HP configuration." I think the builder would also agree with this. 250 is the standard power package, but many decide to upgrade. It could also help on resale.

"Can anyone explain what possible good they are on an 8 Kt boat? " I don't know either. No trim tabs on the new 43 that I ordered.

I have witnessed this re-programming. Cummins tech shows up with his computer, plugs it into the engine ...... Presto ! no other changes. Just for a laugh get a quote from Cummins for that engine as a 220 and a 340. The price difference will shock you.