Yanmar 2YM engine into 34 foot dehler???

[yelbis]

Hi
At present i have a 3gm30 engine 27hp that is difficult to start and leaks through the sump a little. Needs rebuild or replacing.

Does any one know or has experience if a 2YM engine 15HP would be underpowered, as there is one available at a reasonable price. half of that of the 3YM at £6800

Thanks

 

[NickRobinson]

It would be ok for me, my old 4.5t Macwester had an 8hp YSM.. (which I wouldn't recommend, but for the racket, as well as the underpower)

Do you ever use WOT at the moment?

Think of reselling though, will it seem unusual?

 

[vyv_cox]

We went from a Bukh 20 HP to a Yanmar 27 HP in a Sadler 34. The difference has been remarkable. I suspect that 15 HP in the same sized boat would be disastrous.

 

[yelbis]

Well thats two against I suppose. 30 HP it will have to be. Best i start looking for a decent mechanic

 

[corinthmistral]

My friend has a dehler 34 with a yanmar twin cyl approx 18hp engine in her. It's fine, as dehlers are relatively light, and was fitted from new, but a little underpowered in strong seas.

 

[earlybird]

Hi


Does any one know or has experience if a 2YM engine 15HP would be underpowered, as there is one available at a reasonable price. half of that of the 3YM at £6800

Thanks

Is £6800 the basic price? I bought a red 25 HP engine for my 34 ft'er during the 2012 S'oton show for £4440, which included ~£200 of extras & delivery.
If anything, over-powered! 20 HP might have done.
Do a quick shop around, show discounts can be very good.

 

[charles_reed]

I replaced the 2GM20 with a 3YM20. Allegedly both fitted in the same space - but not quite.
The 2GM was just sufficiently powerful for my boat which is lighter and slipperier than yours; the 3YM20 is infinitely better. Quieter, more economical and more powerful, I didn't even have to change the Autoprop.
IMHO, just getting you out and into a berth it would be just adequate - but as a cruising engine totally inadequate.
I spent less than half the price you quote, purchasing a new engine, shipping it to Malta and fitting it (7 years ago).
As already suggested, most of the saving was taking advantage of the LBC discount offered.
Alternatively bypass Barrus and their distributors, buy direct from Yanmar BV, by finding a dleivery address where they have no agent. I understand the 2 additional sets of hands it passes through trebles the price.

 

[onesea]

My friend has a dehler 34 with a yanmar twin cyl approx 18hp engine in her. It's fine, as dehlers are relatively light, and was fitted from new, but a little underpowered in strong seas.

35' 3/4 tonner never tried it into strong seas I am sailing, I would hazard a guess you would be right even a F4/5 in the river knocks the speed down 1/2 knot. I think it depends on how you see your engine, a berthing/ rivers tool or a means to get you from A to B. I am happy with ours but I hate listening to the engine so as soon as I can its OFF...

 

[DHV90]

only thing to consider is that a brand new 2gm is likely to be pretty equal in terms of output to a fairly knackered 3gm, if its low on compression and generally worn out it's quite likely to have lost a fair bit of grunt. is rebuilding the original not an option?

 

[Storyline]

There are others on here that can (and have) give better advice than me but do not forget to consider fuel costs. This is so high these days that you may find that the difference in fuel consumption between a smaller engine being run flat out vs one at cruising revs will pay for the difference over a few years. The fuel consumption of our engine at a comfortable (& quiet) 1800 revs is dramatically lower than if we have to run at 2500+ revs.

 

[Tranona]

There are others on here that can (and have) give better advice than me but do not forget to consider fuel costs. This is so high these days that you may find that the difference in fuel consumption between a smaller engine being run flat out vs one at cruising revs will pay for the difference over a few years. The fuel consumption of our engine at a comfortable (& quiet) 1800 revs is dramatically lower than if we have to run at 2500+ revs.

Doesn't make much difference. Fuel consumption is almost directly proportional to the power being used, not what the engine is capable of producing. So using higher revs to get 15hp out of a 20hp engine will use the same fuel as lower revs to take 15hp out of a 25hp engine. The prop should be chosen to get maximum speed at full revs and cruising at around 70% of peak power (assuming you have a fixed pitch prop).

 

[mcanderson]

I have the 3YM20 in my Beneteau 323 and it pushes it fine in all the conditions I have been out in. My boat weighed just shy of 5000kg at last lift with everything on.

 

[jerrytug]

Doesn't make much difference. Fuel consumption is almost directly proportional to the power being used, not what the engine is capable of producing. So using higher revs to get 15hp out of a 20hp engine will use the same fuel as lower revs to take 15hp out of a 25hp engine. The prop should be chosen to get maximum speed at full revs and cruising at around 70% of peak power (assuming you have a fixed pitch prop).

That sounds reasonable. However in my opinion, "maximum speed " depends on the conditions. Smashing the head into a vertical steep chop, perhaps into a gale, is totally different from gently purring downwind on the rolling billows.
The former needs a big diesel thrusting through a large propellor, bigger the better, as you are going uphill half the time.
The latter needs... not a lot.
I would opt for the 30hp, at least, it doesn't sound much for a 34' if you don't want to limit your cruising by having an engine that won't blast you through the waves when you need it.
(having motored from Poole to Alderney head on into a gale once, in a Sigma, in November, the more power the better)

 

[rudolph_hart]

The 18hp Yanmar 2GM was the standard engine fitted in the VdS Dehler 34, the 27hp 3GM was a factory-fitted option.

I've had 2x 34's - the first had the 27hp the other the 18hp. Although the 27 had noticeably more grunt at the top end, the 18hp was quite adequate (once I chucked the wrong-pitched 3-blade fixed prop in the skip and fitted a correct pitched 2-blade Gori folder).

Hope this helps.

 

[Tranona]

That sounds reasonable. However in my opinion, "maximum speed " depends on the conditions. Smashing the head into a vertical steep chop, perhaps into a gale, is totally different from gently purring downwind on the rolling billows.
The former needs a big diesel thrusting through a large propellor, bigger the better, as you are going uphill half the time.
The latter needs... not a lot.
I would opt for the 30hp, at least, it doesn't sound much for a 34' if you don't want to limit your cruising by having an engine that won't blast you through the waves when you need it.
(having motored from Poole to Alderney head on into a gale once, in a Sigma, in November, the more power the better)

When choosing a prop the objective is to achieve maximum hull speed at near maximum revs in flat water. Of course in adverse conditions maximum speed is likely to be less, and the loss of speed more if there is less power. So, it really depends on what you are looking for - if you just want an engine to get you on and off a mooring and sail the rest of the time then a small engine is satisfactory. However, most people also want the ability to make progress in adverse conditions under motor or motorsailing hence the tendency to higher power engines. You can, though go to far and overpower which means you rarely load the engine properly and have problems of too much power for low speed work.