Not Twins

Mark,
If you spent as money on maintenance as they do you prolly never need a get me home or a 2nd engine. But you're going to bring Janet and her husband and their kids and a coupla his buddies down to the boat to go for an afternoon putz around the harbor. They all just showed up at the house and someone suggested "let's go for a boat ride. Never mind if you haven't been down to the boat for over a month and the battery seemed a little flat and several other maint things are over due they all want to go for a ride and you've always wanted to impress Janet**** ...after all you'll be the captain of the ship.
Lots of trawlers go down to the water in such a state. I think they'd be better off w twins.
Ralph* wrote:
"with twins you are generating TWICE as much heat in the engine room on those hot summer days." If your Naval Architect and/or builder built your boat responsibly your boat would have as much power in either configuration**** ..single or twin** ...and produce the same amount of heat in the ER.

My builder says that even in the beamy 35-foot*Coot,*the primary engine and a genset makes the engine room crowded.* Perhaps a couple of beefy gensets and a single (keel-protected)*electric-motor-powered propeller shaft would be "ideal."* Haven't seen that as a builder-provided option, however.

-- Edited by markpierce on Thursday 10th of February 2011 07:02:12 PM

markpierce wrote:

Seems to me this makes operating twins more interesting....

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One reason I like multi-engine boats is that I like operating the engines and what you can do with them.* This is not to say that one can't accomplish the same maneuvers with a single engine boat. I just like manipulating the engines to put the boat where I want it.

Years ago I filmed on board an oil rig supply boat out of Santa Maria, CA.* This particular boat had three engines.* The skipper had to hold the boat exactly on station under the rig cranes while pipe and whatnot were picked up off the deck.* Port of my filming was of the skipper manipulating his three throttles and shifters to hold the boat in the same spot despite the efforts of the wind and waves to move it.* It was impressive to say the least.* I'd love to be that adept at maneuvering, and that experience is one reason I like running multiple engines.

*

Marin wrote:


nomadwilly wrote:

But about the different brand twins** ..it would be nice if we had someone on here that had experience with such a system and is willing to share.

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Eric--- I will pose your question to the GB owners group and see if anyone responds.


Eric--- FWIW, here is a response I got from Bob Lowe who founded the GB owners site and has many years of working on these (and other boats) as the owner of Oak Harbor Boatworks.* Part of my question was if the differnence in power between the two engines*was compensated for with prop pitch.

(quote)

"Same pitch and diameter and same rpm = same speed, regardless of max hp capability. Assumes props have been sized for any differences in transmissions as in GB twins."

*

Marin wrote:

""Same pitch and diameter and same rpm = same speed, regardless of max hp capability"
Of course. If youv'e got a 500hp engine on one side and a 100hp engine on the other and both shafts are turning 1200rpm both engines are synced and both shafts props are producing the same thrust and power. I thought I covered that. Let us know what comes of the GB site inquiry. In this different engine caper one could get unfortunate enough to wind up w the service side of the engines both on the outboard side.

Mark,
Two small engines (in your case 40hp) shouldn't take up much more (if any) more room than one 80hp engine.

-- Edited by nomadwilly on Thursday 10th of February 2011 10:21:51 PM

nomadwilly wrote:

In this different engine caper one could get unfortunate enough to wind up w the service side of the engines both on the outboard side.

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You could, I guess.* In the case of the AD 150 hp diesel that's a drop-in replacement for the FL120 the base engine for the AD 150 is a new but somewhat similar Ford of England engine.* So the main components--- injection and exhaust--- are on the same sides as the FL120.

*

Yes but the example was w a Perkins and all that service side exhaust side stuff may be or probably is different. Location of engine mounts, throttle, fuel lines, alternator, oil coolers and lots of other stuff will probably be different. Most would be easy to change though.
I joined the GB site but had difficulty w the profile page*** ..the avitar I think.

nomadwilly wrote:

I joined the GB site but had difficulty w the profile page*** ..the avitar I think.

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Which site did you join?* There are two GB owners sites, the International Association of Grand Banks Owners and the GB Beacon site which is hosted by Grand Banks.

The one with the most participation is the IAGBO site.

*

Eric--- Here are a couple of other comments on unmatched twins from the GB site. First one is from a fellow in England who completely rebuilt a near-derelict and rotted out GB32 woody into a near-perfect example of the type and who has a lot of professional experience with engines. Second one is from a local owner of a GB42 woody.

------------------
(1)
Theoretically ? If you had one engine that only developed (say) 70Hp and the other was a 120 you wouldn't notice a difference until the smaller engine couldn't keep up. This would depend on where the power range is on the smaller engine. (look above I stated THEORETICALLY). I don't think anybody would use full power whilst traveling, That said in rough waters pushing against waves etc, the torque difference would begin to show if they were so far apart on the power scale.

With a 120 to 150 I would assume their torque curves would be fairly close.

---------------------
(2)
I second that, if the power band is close at cruising RPM it will not make much difference. As the RPM moves upward and the stronger of the two start developing more and more power, it will make a difference if the gap is large enough. However for a 120 and 150 at 1,800 RPM, the torque curve is close enough between the two engines to make virtually no difference. Give them full throttle and you will have to compensate slightly with the rudders as the power curves separates.

Would it be reasonable to expect that a boat owner would try to match the older engine as close as possible regarding HP,*and torque, as well as any other variables to be considered, well before the new one was installed?**** KJ

KJ wrote:

Would it be reasonable to expect that a boat owner would try to match the older engine as close as possible regarding HP,*and torque, as well as any other variables to be considered, well before the new one was installed?**** KJ

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I would think so.* You want the boat to remain balanced so the weight of the replacement engine should be as close as possible.* And there are considerations like engine mounts, transmission mate-ups, fuel connections, and so on.* This is why American Diesel came up with their engine as it's almost the same as the old FL120 in terms of size and weight and control connections.* And the mounts AD puts on it make it a drop-in replacement.

The 150 hp Lugger, which is popular as a repower for GB32s, 36s, and 42s is about the same size but the mounts are different and it may require a different transmission.* So this engine would require more work to install in place of an FL120 or FL135 be it a total repower or a mismatched replacement in a twin.* I would love to have a pair of these engines in our boat as they represent a signficant improvement over the FL120 in every way except cost--- our old boat does not warrant the cost of repowering as long as the two original engines are operating.

*

nomadwilly wrote:

Yes but the example was w a Perkins and all that service side exhaust side stuff may be or probably is different. Location of engine mounts, throttle, fuel lines, alternator, oil coolers and lots of other stuff will probably be different. Most would be easy to change though.
I joined the GB site but had difficulty w the profile page*** ..the avitar I think.

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HELLO!* This is why I called it "wrong" in the first place.* Heck, I compared it to hiring a hooker to kick you in the nuts!* One Perkins is hard enough and two is even harder.* So why would someone put a Lehman and a Perkins in the same boat when they could get an AD which is pretty close?* It is like putting a Mercury and an Evinrude on the same boat...* Well maybe not that extreme*

*


-- Edited by Egregious on Friday 11th of February 2011 08:19:36 PM

nomadwilly wrote:

Mark,
If you spent as money on maintenance as they do you prolly never need a get me home or a 2nd engine. But you're going to bring Janet and her husband and their kids and a coupla his buddies down to the boat to go for an afternoon putz around the harbor. They all just showed up at the house and someone suggested "let's go for a boat ride. Never mind if you haven't been down to the boat for over a month and the battery seemed a little flat and several other maint things are over due they all want to go for a ride and you've always wanted to impress Janet**** ...after all you'll be the captain of the ship.
Lots of trawlers go down to the water in such a state. I think they'd be better off w twins.
Ralph* wrote:
"with twins you are generating TWICE as much heat in the engine room on those hot summer days." If your Naval Architect and/or builder built your boat responsibly your boat would have as much power in either configuration**** ..single or twin** ...and produce the same amount of heat in the ER.

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Eric NomadWilly said "If your Naval Architect and/or builder built your boat responsibly your boat would have as much power in either configuration**** ..single or twin** ...and produce the same amount of heat in the ER."

This just doesnt make sense. We all know of trawler boats in the same make/model that are available in either single or twin. How can a single in the same boat generate the same amount of heat in the ER as twins in that boat?
And how can twins equal the same amount of power as a single?
First off, the owner of a brand new boat being ordered for build chooses twins for a different utility than a different owner ordering the same boat with a single. Marin said it correctly...each has different uses in mind and therefore one is not necessarily RIGHT or WRONG.
I didnt mean to imply that one was right or wrong either but rather that the benefits that many owners espouse about twins is not what its cracked up to be.
Having the ability to "get home" is an expensive insurance cost by adding that second engine. And it ignores the REAL reliability of the engine that is properly maintained. It also ignores the probability of a maintenance action required on EITHER engine that prevents the owner from leaving the dock. The likelihood of this occurring it TWICE as much in a twin engine boat as a single.

Twin engine owners never seem to grasp this probabilistic outcome.....or if they do, they seem to ignore it.

R.


*

ralphyost wrote:
The likelihood of this occurring it TWICE as much in a twin engine boat as a single.

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On the other hand, when an engine does fail or have to be shut down on a twin, even though it is theoretically twice as possible, you still have that other engine to get home with

As to the twice-as-much-risk thing, this was widely bandied about in the commercial aviation business when in the early 80s when airlines, manufacturers, and regulatory agencies began exploring ETOPS--- extended range, twin-engine, operations.* Running two engines is more economical in many ways besides just fuel to running three or four, so there was a big desire to operate twins over longer and longer distances.

Initially there was a lot of resistance to the notion of flying across the Atlantic or Pacific with "just" two engines.* A popular argument for awhile in favor of two engines was if you have four engines the odds of an engine shutdown is twice what it is with two engines.* But while in a simplistic way this is true, the fact is that in an operational way it isn't.* I produced a video about all this way back when we were positioning the 777 against the A340, and the reality was the actual engine experience regarding in-flight shut downs does not bear out the "the more engines the more chances for an engine shutdown" theory.* So we sort of dropped that reason from our campaigns.

As I've stated previously, we've had to shut an engine down four times in the twelve-plus years we've had the boat.* As it happened, three of those times, which were due to cooling issues, were on the port engine although the problems had nothing whatsoever to do with the engine itself.* Had the boat been a single and the same things happened, we still would have had to shut the engine down.* The fourth shutdown was the starboard engine because I let it get a big slug of air during a fuel transfer which was my mistake.* So again, had it been a single engine boat, the same mistake on my part would have killed the engine.

So I don't put any stock in the "twice the probability of an engine shutdown" in twins theory even though statistically it is correct.

And here's a statistic to ponder.* The now-retired owner of the diesel shop in Bellingham told me when I made some comment about how when we had a problem it always involved the port engine that their records showed that over the years, the most troublesome engine in twin engine boats was usually the port engine.* He had no explanation why, it was just what the numbers showed.* So for anyone contemplating having a twin engine boat built, make sure you specify two starboard engines.* This will greatly lessen the probability of having an engine problem


-- Edited by Marin on Tuesday 15th of February 2011 02:47:00 PM

Got sails?* They*often work when you've run out of fuel.* Even twins can't save you then.

markpierce wrote:

Got sails?* They*often work when you've run out of fuel.* Even twins can't save you then.

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Very true.* On the other hand, if a person runs out of fuel I think they probably deserve whatever happens to them.* Chuck Darwin's theory, you know.....

Marin wrote:


markpierce wrote:

Got sails?* They*often work when you've run out of fuel.* Even twins can't save you then.

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Very true.* On the other hand, if a person runs out of fuel I think they probably deserve whatever happens to them.* Chuck Darwin's theory, you know.....But you and I have a legal and moral*imperative to*save that person to the extent practical and safe for us.

*

Ummmm............ no.

A current news article states:

"Vessels ignored multiple maydays from a sinking ship in the Channel last December
"A NUMBER of merchant ships ignored multiple distress flares and maydays from a sinking fishing vessel in the Channel last December, in apparent dereliction of one of the most fundamental duties of the mariner, according to an official Marine Accident Investigation Branch publication.

"One fisherman died as a result, leading MAIB chief executive Stephen Meyer to accuse some merchant vessels of failing to meet the longstanding legal and moral obligation to go to aid of those in peril on the sea. The former admiral has personally taken a number of shipping concerns to task directly as a result.

"A possible explanation is that commercial pressures left masters feeling unable to respond, simply because that might have left them behind schedule, a trade union official has suggested."

Now assume the Darwin candidate has given out a Mayday.


-- Edited by markpierce on Tuesday 15th of February 2011 11:48:06 PM

markpierce wrote:


Now assume the Darwin candidate has given out a Mayday.

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My tax dollars at work.* That's why the USCG monitors Channel 16.* We don't.

*

markpierce wrote:Now assume the Darwin candidate has given out a Mayday.

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Just because some fool runs out of fuel and calls mayday doesn't make it an emergency. If the crew is not in a life threatening position and boat is not in immediate danger of sinking even the CG will tell the guy to call for commercial assistance.

If the fool has a sail and is not on fire, sinking, or about to be blown on the rocks of a lee shore the fool should be on deck, not the radio. You can buy a boat, you can be an idiot, but you can't expect anyone else to participate in your fantasy.

That is part of "yachting" that isn't in your owner's manual Grasshopper.


-- Edited by RickB on Wednesday 16th of February 2011 06:06:20 AM

Got sails?
As a past owner/operator of a SEA-Tow licensed area, we always heard from sail boaters at the boat shows "we never need seatow we have sails!" The reality of the sails is that 1/2 of our towing work was sail boats. It seems that there was to much wind, not enough wind, etc. This does not include groundings/refloatings, just tows to the marinas.
I once ran from Boston to Gloucester (about 23 NM) to tow in an almost new Shannon, whose owner was just tired of sailing.

Yup.

Seems to me as many mid-size/large sailboats are using their*engines as compared to just sails outside of marinas.

No guarantees out there, but it is good to have options.

Hey Jack,
I wonder if he went home and bought a motor boat.
Benn

I would hope he did. It seemed to me that he would have gotten more enjoyment out of a power boat. On the other hand, he didn't make excuses for his behavior (or blame his wife!) He ponied up the cost and let it go at that.

Here in SE Alaska quite a lot of sail boats come up and cruise all around*** ...under power. I'd say they sail less than 5% of the time. Sail boats are More efficient than even full disp power boats but the outside wheelhouse and extra deep draft is not good up here. Every day you see them in their yellow slickers clutching a hot cup of coffee w cold and wet hands. When I was looking for a trawler I was also looking for a drop keel sail boat I could convert to a trawler. Tear off the sail gear and all the deck and cabin. Place the engine and tanks and all the other heavy stuff in the center of the hull w some aft to dampen the pitching moment. Keep the bow light so it will rise up to the sea instead of going through it. The wheelhouse would be high and a midships providing a large engine compartment.
I could have a 40' boat much more seaworthy than Willy and at the same fuel burn.
Too much work for me but I like ideas.

We have been working on a concept of a center board FOR the offshore power cruiser.

The board slot would be extra wide , and the board would be built so when extended it could be pivoted from side to side.

This would serve as a stability device , with out the cost or grounding danger of side fins.

Run aground, the board would simply kick up as they have been doing on sail boats for centuries.

Air pressure from a truck engine mounted compressor would be power with no cooling as required by hydraulics.