From my earlier post:
However, the marinized Kubota based Beta 13.5 hp or 16hp 2cyl really looks like an easy swap for the 2QM15...takes the Hurth ZF I already have...dipstick on the right...impeller swaps from the front...optional pump for oil changes built in. Therefore I could save an easy $5K if I did it myself and this engine (and perhaps other 2 cyl) would make it easier to do it myself. With the 16hp I could even bump hp by 10%. Currently with my 2QM15, which is 14hp, and the factory 2 blade Michigan wheel prop I can only hit 5.5 knots, about a knot shy of hull speed. Ideally the new engine would allow me to cruise at 6.5 knots at its specified cruising RPM.
I'd also by lying if I told you that I wouldn't look hard at Yanmar first though. The equivalent engine is the 14 hp 2YM15.
Vetus is a big marine supplier selling Vetus branded marinized mistubishi diesels. However, they seem to have abandoned the engine market, as I can't find a link to buy one or a local dealer on the internet.
Westerbeke is another strong contender. It is much better known that Beta, plus there is an 18hp 2 cylinder (20B) that sounds attractive. It is just a hair smaller than the 2QM15 (26L x 20H x 20W versus 27.6L x 18W x 22H for the 308lb 2QM15) and much lighter at 225 lbs. The 27 hp 30B is the same as the 20B barring an increase in length to 30 inches and weight to 274 lbs.
The beta, at 16 hp is a 10% improvement in hp over the 2QM15. If you are doing it yourself, in my opinion, if you are only going to do limited coastal cruising a like-for-like replacement like this is fine. I had my 2QM15 in the Cape Cod Canal running against a 3 knot current! (Captain read the wrong week on the tide chart). We got there. It just took more time. However, if you are planning to cruise extensively a bigger engine is probably necessary to get you to hull speed (6.5 knots) and a knot an hour isn't anything to sneeze at if you are on a long passage.
I'd be really tempted to shop for a price on that 2cyl 18 hp Westerbeke if I were you. That is a significant increase in hp (4hp) in a small package. The small package is a plus as your engine access probably isn't great. A new engine is definitely a plus at resale, but if someone is shopping the 9.2C hard the larger engine will be a big plus. Bayshore in Annapolis is a local dealer.