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Old 30-01-2011, 16:10   #16
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Salty,I Sent u some info.,from browsing the net.
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Old 30-01-2011, 16:26   #17
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Lots of good advise above. 13hp? Sounds a bit weak but I agree that with skill and patience, its workable. Under calm conditions 5hp ought to be plenty and the extra is just to push against wind or current when you wish to fight mother nature instead of live in harmony with her. I have towed my 23,000 boat around the harbor at a comfortable speed with a 2hp dingy when I had engine problems.

It seems to me like the first issue to resolve is whether you have the option to overhaul the engine. So get it out and take it apart and see what's inside. What's to loose?

I've overhauled a few engines and never by choice, but I'm glad now that I did it. If you are the least bit inclined to give it a try, I'd encourage you to try. 13hp diesel engines are not rocket science and there is a world of help, advise and information here on the internet--unlike when I did it.
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Old 30-01-2011, 16:32   #18
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Horsepower is far less important than torque. the torque curve of your existing engine is more than sufficient to drive your boat at hull speed, so rebuilding your existing poswrplant is probably your most cost effective route. BUT, the only way to know for sure is to know for sure. Pull the head, and take it to a machine shop and have them scope it and magnaflux it. if there are not cracks or thin spots in the head, then do a three angle valve job, lap the head , install new gaskets, torque her down, and sail her like you stole her.
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Old 30-01-2011, 16:52   #19
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I have a 30yr old boat with a raw water cooled volvo in it. I was having problems with it last year and I decided to rebuild it. I am a auto mechanic by trade so I did all the work myself. I spent 3800 in the end fixing my 30 yr old volvo engine that although it runs great I still get nervous trusting it. For 6500-7000 I could have repowered with a beta that is lighter smoother and quieter. I should have scrapped the boat or repowered. Biggest mistake of my boat owning carrer was rebuilding that old raw water cooled motor.
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Old 30-01-2011, 17:01   #20
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We often talk about repowering...except our old very old volvo with an uncertain amount of hours always runs, and never misses. We are a bit underpowered but see above. Still before we undertake another long trip, we will repower. WE have done some research and know what engines will fit the footprint. Oddly enough more power will ultimately take up less room. Everything on a boat is a trade off...so one has to decide what is most important to them. Try your boat in various current, wind and wave conditions and see how she behaves. That will help you make your decision.
Cheers and Fair Winds
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Old 30-01-2011, 17:17   #21
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Rebuilt motor raw water should still be good.
Ideal minimum 1 hp. for each 500 lbs. total weight boat, tankage, provisions and crew plus correctly sized/ pitched prop. That should be around 24 hp plus when provisioned for cruising.
Usually these formulas are approx rule of thumb. 13 hp will get you in and out and down the ditch under benign conditions but if the question "is this motor to small for comfortable
coastal cruising? You will find yourself under powered at times.
Will you feel comfortable with that.
Other considerations beside moving boat, what else will be running off motor (sapping hp) while you are cruising?
Hugo
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Old 30-01-2011, 17:31   #22
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Using horse power is a bit misleading
SS Great britain was powered by 1000hp engine turning at 18rpm
The modern equivalent Rolls Royce Olympus puts out 70,000hp at around 10,000 rpm
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Old 30-01-2011, 18:14   #23
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Rebuilt motor raw water should still be good.
Ideal minimum 1 hp. for each 500 lbs. total weight boat, tankage, provisions and crew plus correctly sized/ pitched prop. That should be around 24 hp plus when provisioned for cruising.
Usually these formulas are approx rule of thumb. 13 hp will get you in and out and down the ditch under benign conditions but if the question "is this motor to small for comfortable
coastal cruising? You will find yourself under powered at times.
Will you feel comfortable with that.
Other considerations beside moving boat, what else will be running off motor (sapping hp) while you are cruising?
Hugo
I know that this is a currently accepted rule of thumb, but I love how inflation works. Eric Hiscock, Cruising Under Sail -

"For normal cruising purposes one horsepower per ton of displacement should be sufficient ... But if the yacht is to be capable of making good progress against a headwind and sea, or to reach her maximum hull speed under power (some owners feel this is essential) at least 3 horsepower per ton will be required."

So today's minimum is 4 hp per ton, and probably 4.5 hp per ton as I believe he would have meant long ton, 2240 lbs/ton.

John
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Old 30-01-2011, 18:49   #24
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G'DAy,

I won't chime in on the how much power do you need controversy, but would remind you that changing from your old, relatively low RPM engine to a more powerful, higher revving one will likely require a change in both shaft and prop. This adds significantly to the cost of re-engining!

Cheers,

Jim
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Old 30-01-2011, 18:51   #25
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Wow! Thanks for the great responses. One of my concerns with rebuilding the existing 2QM15 is that I don't know how badly the block is corroded in side from all those years of saltwater (brackish really in the northern Chesapeake). I know when I remove the hoses from the engine to the hot water heater, they are almost totally plugged with deposits. That's another reason for FWC -- Real Hot Water for the boss. I'd guess that a remanufactured FWC engine is going to be a better long term deal. I guess I'm still a little torn as to which engine I should be looking for: 2GM20F or a 3GM30F or something else altogether. Would a 2GM20F fit in the same space as the 2QM15?
Look at the Nanni/Beta line of diesels...easier access and "tractor spares". The logic of a rebuild after 30 years is unknown, but if the passages are that fouled, I would hesitate to estimate the amount of metal wastage.
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Old 30-01-2011, 18:56   #26
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I was in a similar situation last year: my old 18hp raw water cooled Sabb diesel ran well enough but needed some work. Since I built the boat around the engine I didn't have a lot of room to work with, and I had to carefully measure each prospective engine (and found most of the 38hp engines fit). I decided on a new engine because the newer technology results in a lighter, more powerful engine in the same space. Most of the time I won't need that power, but I have spent too much time slogging to weather at 1 knot to get into port to want such a small engine again. New engines are also a lot quieter and cleaner than the old ones. The fuel consumption is only an issue if you actually use that extra horsepower - I expect at 5 knots to do at least as well as the old engine. If I am driving hard into heavy going then I will be happy to pay for the extra fuel used to bring the experience to an early end. And of course a new engine means a long honeymoon before problems start arising with the engine. So consider a new, more powerful engine as another alternative.
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Old 30-01-2011, 19:44   #27
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the QM series if fast becoming extinct. Move up to a GM or even better a YM
I'd vote for an upgrade to new motor!
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Old 30-01-2011, 20:38   #28
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Unless your pockets are really deep, I'd at least tear it down and see if rebuilding is easier. If you tear it down in place and decide it isn't worth it you can take the pieces off the boat by hand, and use the travel lift only once to drop the new engine on the new mounts. If you choose to rebuild, gaskets, pistons, rings, bearings, headwork, injectors, fuel pump...$2000-$2500, I did a 8hp for $700 a dozen years ago. Good Luck, whichever you decide.
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Old 30-01-2011, 21:43   #29
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G'DAy,

I won't chime in on the how much power do you need controversy, but would remind you that changing from your old, relatively low RPM engine to a more powerful, higher revving one will likely require a change in both shaft and prop. This adds significantly to the cost of re-engining!
And, possibly, new mounts, which could entail building new stringers. And a new exhaust system. Oh, and a new fuel tank.
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Old 30-01-2011, 21:53   #30
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And, possibly, new mounts, which could entail building new stringers. And a new exhaust system. Oh, and a new fuel tank.
And a new hoses, thruhull, prop shaft, cutlass bearing, shaft seal, stern tube, strut..........

Re-power means re-build motor compartment. Go ahead, ask me how I know.

But now it's just shy of being a new boat.
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