H280- 2YM15 or 3YM20

[Ken13559]

My friend is planning to repower his 1994 H280 existing 1GM10 to either 2YM15 or 3YM20 (both engine recommended by Yanmar). From brouche the 3YM20 is supposedly a drop in replacement for 2GM20F and I know another H280 has the factory option of 2GM20F. So I guess the 3YM20 should fit the H280 engine compartment. Question is, is the 3YM20 (21hp) over powered for this boat since the displacement is 6200 lbs. Going by current yardstick a 6200 lbs displacement requires 12hp.

 

[Ed Schenck]

The YM's are very small and light diesels. I installed a 3YM30 in my H37C. The dimensions and weights can be found on the Yanmar site I think. So I am sure that size and weight would not be the issue. One might fit slightly better but neither will install right on the old mounts. So I think you are right, it is a horsepower issue.

For inland lake or always good conditions then obviously the 15 would be adequate. But in tough conditions maybe you want to swing a big 3-blade. Then you need the 20.

 

[Steve Dion]

Ken: If you friend was okay with the power of the 1gm10, then the 2ym15 should be more than adequate with 50% more power. The key to any engine is really the correct prop.

How much difference in cost is there between the two engines?

The rule of thumb is 1hp/500 lbs. I do not know if the specs on these boats were wet or dry. It is not too difficult to add 2000-3000 lbs to a vessel with fuel, water, waste gear, etc. Just use 8 lbs/gal for starters and go from there.

 

[amcmahon]

Steve, About 4 years ago, I replaced the Westerbeke 10Two in my 1984 H27 with the 2YM15. A great fit and great engine. The H27 displacement is about 7500# and with a clean hull and prop, I can reach theortetical hull speed at about 2500 rpm. As I approach bottom paint time, I still get full speed by 3000 rpm. I have a three blade and the top noload rpm is about 3800rpm, so pleanty of extra power. I boat in a high current river environment so strong engine is essential. Your friend will also get better fuel effeciency with 2YM15. Good luck. Tony

 

[Ken13559]

Thanks for the feedback. My friend's 8hp is totally inadequate for tidal waters here. There were ocassion where his boat sort of break-even with the tide. He felt like driving through the Deception Pass in one of the Youtube video. He had wanted to install 3YM30 but I think thats too much hp and size. We will measure for 3YM20. If that won't fit then its 2YM15.