Is it worth $3-5K to get a 2GM15 instead of a 1GM12?

[BobM]

I am looking at a number of S2 9.2a's in the area 1978-81 vintage. Most have a 2cyl 15hp yanmar (2GM15?) and are 18-22K, but one boat has a 1GM 12hp. It is substantially cheaper at 16K, even though it is no slouch in other areas on paper. I am going to see it today.I am well aware that even 15hp isn't a ton of power for a 10,000lb 30 foot boat, so please try to stay on topic ;-)The question is...all other things being equivalent...is 3hp really going to make that much difference? I am mechanically inclined, but not a mechanic...I think that perhaps the 2cyl will supply more torque along with more hp, so perhaps hp is deceiving.I also try to use the 80:20 rule to some effect. The lower hp would suffice for over 80% of my routine sailing activities, but in sailing one must also take safety into account.Any personal experience from owners with similar boats / hp are greatly appreciated and of course all and sundry are welcome to opine.Thanks in advance for the shared wisdom.Bob

 

[Smooth Runnings]

2cyl = less vibration...

I would recommend using the 2cyl just on the vibration issues alone..

 

[Ed Schenck]

Sailing grounds.

Given your address it seems that you would want the extra power. Cheap as I am though I would buy the smaller engine if the boat was substantially nicer than the more expensive ones. The previous post is worth thinking about, the one lungers do make a racket.P.S. Just read "Cap'n Jim's" response. Good point, it would have to be a 1QM15. Point being that the 2QM is a very heavy engine. I had a 2QM20 in my H37C. My new 3YM30 is over 250 pounds lighter than the 2QM!

 

[filthy liberal scum]

i would say that 12hp is too small!

I have a 1979 O'day 30 that weighs 11,000# and it has a 2QM15 and is just adequate. has either engine been replaced? i'm not sure but i don't think the GM series was in production yet for those years. the 15 hp engine would be fine but i think that the 1 cly 12hp would be too small. thats way below the recommended hp for a 10k boat.S/V Que Pasa?

 

[Rich (P303)]

Yanmar 2GMF

is O.K. on my 1984 Pearson 303 (13HP). I would not want anything less. I would like to have more HP in the tidal area I am in.

 

[Maine Sail]

Rich..

Quote Rich: "I would like to have more HP in the tidal area I am in."You? In a tidal area? You don't say! That's the understatement of the week!!!;D

 

[Paul Akers]

Being from Winthrop, MA...

...Which is near Boston, I would think that the tide runs at a difficult rate very often, even if you were to occasionally go to the Cape Cod Canal. You have higher tides in Boston than South of the Cape. IMHO, Go bigger!I had a friend that use to have the 1 cylinder on a 25' Bayfield and ALWAYS had a problem keeping up with the fleet. Plus he could never get hot water unless dockside where he would plug it in for the admiral.

 

[sailaway78]

Horsepower

Yanmar rates the horsepower at wide open throttle. And their manuals tell you that you should not run at wide open throttle for extended periods of time. I think the 2QM says no more than three hours continuos. I think you are talking about more than a 3hp difference at say 70 or 80%. I have a 2 QM in an S2 8.5, which is almost the same hull as the 9.2. I wouldn't want the 12 on the 8.5.

 

[TT23844]

Raw water cooling ???

The 1GM12 may be raw water cooled while the 2 cyl engine is FWC.Despite the additional maintenance requirements of a FWC system , having the engine block, head etc continually immersed in a corrosion resistant anti-freeze solution should make for longer engine life & more efficient operation due to the higher running temperature. Also, a FWC system is more amenable to providing heat for domestic water ( eg a shower).Well worth the extra $$$

 

[Ross]

I have a volvo model 2001 single cylinder 10 HP engine

it weighs close to 300 pounds. It is able to push the boat as fast as we can sail most of the time. It is used primarily for flat calms and docking. The little that we use it keeps the batteries up. There are those that say you should run the engine at 75 per cent of its rated hp but it is hard to do that with a big engine and a displacement hull. There is simply a limit to how fast a sail boat can go.

 

[sailaway78]

I think that is a 1QM

Not exactly sure when they started the GM series engines, but 1980 is a QM. The engines you are looking at may or may not be fresh water cooled. More than likely it is raw water cooled.

 

[higgs]

One cylinder

I recently was aboard a friends Irwin with a single cylinder diesel and I certainly would not want to motor any distance in his boat. It reminded me of the single cylinder gas engine I had in my old Paceship Eastwind, a boat I owned and cruised for 14 years. When I got rid of the boat I promised myself never again to own a one lunger.

 

[Landsend]

2 cylinders...you won't regret it!

but you will regret it if you only get the one cylinder engine. Kind of like: "Wow, I could have had a V8!'

 

[filthy liberal scum]

did a little search on yanmars

here's the scoop. 2QM15 built 1977 to 1980. 2GM built 1980-83. 2GM20 and 2GM20F built 1983-04. first two had hp rating of 15, 20series had 18hp rating. don't know about the one lunger.S/V Que Pasa?

 

[Liam]

Go for 2 cyl

Back in the 80's I had a single cyl Yanmar. The vibration not only drove me crazy it also caused the motor mounts and head bolts to constantly vibrate loose (and every other screw and bolt on the boat). It only had enough power to push the boat in and out of the slip or motor in dead calm.The good news was that I could hand crank it to start.Get an engine survey / oil analysis in either case. Replacing a diesel (even a small one) will cost you $15K min.

 

[Big Windy]

HP

Yanmar recommends one HP for each 500 lbs of boat weight.

 

[Ross]

Yanmar sells engines!! Only if you insist on being able

to push up against hull speed with an engine do you need that much power. In calm flat water I could row my 9500 lb boat at 1 knot. I calculate that I use about 4 hp to push the boat to 4 knots. Horse power cost money when you buy it and when you use it.

 

[Jim]

It is nice to have a boat that can do hull speed

when you travel. If you sail where there is little of no current and never ever travel and under power boat is ok.

 

[Jim]

Bob, how much is your boat worth and

why do you have to repower? For 18-22K you should be able to get a new used boat in the early 1990s. One with a swim platform and a 2GM20 engine.Every boat has a date with a chain saw! Just like we have a date with the grim riper.

 

[BobM]

Thanks to all for your opinions and info

We sail in Boston Harbor and will hopefully do some coastal cruising with the new boat, whichever one we select and can strike a deal on. Of immediate concern is the likelihood that we will have to take the boat through the Cape Cod Canal if it is south of the canal to start with. It shouldn't be too much of a problem if we time it correctly, slack tide or tide flooding to the north. Other than that, the need to make way against the ocean is always something of a concern, so I appreciate the advice and will likely stick to the 15hp 2 cyl at a minimum. I also emailed about one with a newer 27hp diesel engine...but it is an old listing...thought I'd try to waterski ;-)We looked at the boat with the 1 cyl 12 hp engine on Saturday. We decided that we do like the 9.2A, especially the cockpit, which is important as we do a lot of day sailing. At this point we are keeping that boat as an option, but her overall condition was marginal. I'd rather pay a few more bucks a month than spend the spring on repairs, especially with the boats current location, which is 90 minutes from home...not too much of a hardship, but certainly something to think about when considering many potential trips to repair her to make her seaworthy again. Especially given the fact that her longest trip of the season will be one of her first.We are looking at a couple of others with 2 cyl 15 hp, including one that has had a lot of significant recent investments. Bob