Inboard Engine Recommendations?

Hey all, for a while now I've been thinking of building Ken Hankinson's "Sweet 16" minitug (see picture below) but I don't have very much experience with inboards and I was wondering if anyone had advice as to what a good inboard would be in the range of 20-30 hp. Thanks!

I often suggest that you should consider who would service the engine, especially under warranty. Would the boat be near the larger boating centers such as Nassau, Freeport or Marsh Harbor? What do the engine manufacturers say about service and warranty outside of the US?

In that engine hp range, there are really only two major manufacturers: Volvo- the D1 and Yanmar- the 3YM20. 99% of the 25-32' sailboats built in the world have those engines.


But there are a couple of other options. Beta Marine has a line of nicely marinized Kubota engines. Service won't be as ubiquitous as the majors, but Kubota's are used everywhere for tractors and construction equipment. Nanni is another marinizer of someone's block, but AFAiK there is no dealer support in NA, but popular in Europe.


David

You could go w a Honda single or twin air cooled engine. Ten hp is plenty for your boat. I've seen a 26' Fisher w a single cyl 10hp Yanmar.

You didn't even specify a preference for diesel or gas. I recomend diesel mostly for safety but it will be very noisy unless you get serious w sound insulation. Vibration could be an issue w the metal boat. David is right .. a used sailboat engine would probably be best. Good compromise of many things.

If you can find one a Brennan Imp of 25hp (1950's) would be very quiet and smooth or perhaps another old gas flat head marine engine. CL is about the only place you'll find one though.

An OB would be easy and quiet. A 9.8 hp 4 stroke mounted on a bracket on the stern or in a well aft. The latter would need a fan to deal w the exhaust fumes.

Let us know what you find.

I would take a look at Phasor. They primarily offer generators with Kabota engines, but also offer propulsion. For as many generators are sold with Kabota motors, it would be my first choice as engine parts should be easily attainable.

Phasor Marine Propulsion

Ted

As others have said its pretty much either the volvo or the yanmar - I would shy away from an air cooled engine as its going to be loud and also short lived in the kind of continuous duty application you are thinking about. Kubota diesels aren't as common in this application but they are super easy to work on as they are designed for farm tractors and end user maintenance - how that translates to your particular ER though would be a good consideration for the people doing the marinization.

How did I forget Westerbeke in my post above. While big in marine diesel generator's, Westerbeke's position in small propulsion engines has diminished. But they still are a significant player.


You need to research the EPA regs for a new build. It used to be that marine diesels under 50 hp were exempt from the Tier 1,2,3,X regs, but now I don't know. I realize that the Bahamas may not care much, but you probably will need to source your engine in the US and they won't carry an engine if it doesn't meet EPA specs.


Maybe a better way is to look for a used sailboat engine. Bayshore Marine, Mac Boring and others rebuild Yanmars to near new specs. You could get a rebuilt one shipped to the Bahamas, but check for customs restrictions.


David

As others have said the options are Volvo-Penta, Yanmar and the various companies that marinize Kubota engines (Beta, Nanni, Phasor). Other options include Vetus and Westerbeke (marinized Mitsubishi engines).

Volvo and Yanmar are big international brands. Beta is out of the UK with north american distributors. Nanni is a french company with a small US distribution network. Vetus is dutch and Westerbeke is out of Massachusetts in the US.

I would look at what distributors there are in the Bahamas.

All of the above offer engines in the 15-30 hp power range.

djmarchand said:

How did I forget Westerbeke in my post above. While big in marine diesel generator's, Westerbeke's position in small propulsion engines had diminished. But they still are a significant player.


You need to research the EPA regs for a new build. It used to be that marine diesels under 50 hp were exempt from the Tier 1,2,3,X regs, but now I don't know. I realize that the Bahamas may not care much, but you probably will need to source your engine in the US and they won't carry an engine if it doesn't meet EPA specs.


Maybe a better way is to look for a used sailboat engine. Bayshore Marine, Mac Boring and others rebuild Yanmars to near new specs. You could get a rebuilt one shipped to the Bahamas, but check for customs restrictions.


David

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This is a good point - all the new Kubota engines above 25HP need to have a DPF with regen to meet tier 4 standards - I don't know how this translates to marine applications although they obviously aren't using extreme exhaust heat!

I agree with the Volvo/Yanmar. I've dealt with both, Volvo in Europe, Yanmar over here. For that reason I would lean to Yanmar. Don't under power. Those extra horses come in handy when the bliss turns to snot, if you get my drift.

Get the smallest three cylinder you can get. The Kubota's marinized by Beta are nice. Quiet engine at mid range. A two cylinder is an obnoxious infernal beast. Lots of vibes and sounds sick too. Three's are much better.

Go with a Beta(Kubota) 10 or 14 if you don't mind the noise and vibs of the 2 cylinder or follow Skys advice and go 3 cylinders. I have the motor on my 18 ft cat boat real easy to service and its a kubota. I have had a few Kubota motors on tractors in the past and they were very good. You are going to go hull speed and maybe use 6 HP to get there. The K 14 also comes in a tuned down 10 HP version and would probably be enough but the extra 4 Hp won't cost much more or burn any more fuel at the rpm you use it and nice to have.

Ski in NC said:

Get the smallest three cylinder you can get. The Kubota's marinized by Beta are nice. Quiet engine at mid range. A two cylinder is an obnoxious infernal beast. Lots of vibes and sounds sick too. Three's are much better.

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I agree.

Ski in NC said:

Get the smallest three cylinder you can get. The Kubota's marinized by Beta are nice. Quiet engine at mid range. A two cylinder is an obnoxious infernal beast. Lots of vibes and sounds sick too. Three's are much better.

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Hah! You want to talk vibration? Spent some formative years on Dad's boat with a 10 horse ONE banger..... I mean, my fillings were coming out......

Just looked up the Beta line up and it looks like 20 HP is smallest 3 cylinder. That would certainly run quite and smother than diesel 2 cylinders but why not a ten or fifteen HP gasser?

Thanks to all who answered so quickly, from what I've seen during my research it sounds like one of the easiest to find would be a Honda, Kubota, or Yanmar. Also, I realize I forgot to update my profile, but I no longer live in the Bahamas, I live in Utah now, so I probably should look up the regulations beforehand. Secondly, I'm planning on building the boat in plywood, just in case that influences the decision, and thirdly, I prefer diesel engines over gas, so I'd be looking for a diesel inboard. But anyway, all these responses have been very helpful, so thank you all!

eyschulman said:

Just looked up the Beta line up and it looks like 20 HP is smallest 3 cylinder. That would certainly run quite and smother than diesel 2 cylinders but why not a ten or fifteen HP gasser?

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No gas on my boats..... Yes I know, gazillions of people have done it safely for centuries.

I just can't forget the few that didn't.

oscar said:

No gas on my boats..... Yes I know, gazillions of people have done it safely for centuries.



I just can't forget the few that didn't.

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My friend & mentor, who I worked with on charter fishing boats, Capt Dave Willoughby got blown 50' before he hit the water. He survived, boat burned to the waterline. He was on this boat assisting. I will never forget that blast. No gas allowed. Dingy tank remains topside.

My vote too, would be for A Honda or a modern yard implement V engine.like a pro series Briggs and Strattin

Gas is far more tolerant of poor fuel and does far better with light loads.

The entire engine cost (about $1,500 US ) is less than having a diesel injector pump rebuilt or a few injectors replaced.

The ease of silence aboard would be as important as the cost factor .

The lower cost of oil and filtration , and the ease of local service anywhere would also be a big plus/

If you were commercial and going to use the boat 1,000 ..2,000 a year there MIGHT be a saving in fuel that would offset the higher cost of diesel purchase and maint.and storing.

I don't think air cooled gassers are allowed at all as inboards, and for a few good reasons.

The cheapest diesel is USED at your local Big Truck Reefer repair.

Frequently 3 engines can be had , all running take outs for about a grand.

Only one may run $400 or more.

These are water cooled Kubotas or Yannmars and have the huge advantage of very over sized oil pans , to keep them running with no help for a week.

A tiny keel cooler , exhaust wrap and a dry stack would require no marine $toopid priced items to Zero!.

With a hatch in the overhead an engine change would be an afternoon, if that of work.


If installing a diesel I would attempt to locate a gen set noise box set , bottom to top , and install it in that.

If you need a tranny I have a Volvo from an MD 6 18hp that would be fitted with only an adapter plate. $400, plus shipping. Cable shift F N R

Ply boats are OK but an outer covering of GRP or Dynell set in epoxy is worth the extra cost and effort.

Whatever option you choose wish you all the best and am hoping you will document your build online! I love following people how have the commitment to build their own boats.