I took the engine in yesterday - still waiting to hear what the mechanic found.
But I did talk to him about engines and mounts, and did a bit more searching online.
Regarding hitting something - No, I don't think so, but there may have been acute stress. It was _just_ after putting into reverse (ie. the stress of shifting gears). I had the RPM somewhat higher than normal (about 2000rpm-2500) and was revving the engine back up to avoid stalling. I suspect that the gear shift was the straw that broke the camel, and did most of it in, then rev up took the rest to falling off. Hard to say exactly, though. Everything seemed to happen very quickly.
I don't think the bolts are bent up. I'll check more closely, but I think thats just an artifact of the fact that they are free floating above the bottom part. The look strait to gross observation in real life.
The mechanic had not personally seen the plastic boards breaking, but was always suspicious about them, and had heard stories. Also, I found a couple of other reviews on a mount that looks nearly the same as mine. http://www.westmarine.com/buy/west-marine--replacement-2-polyethylene-mounting-boards-for-outboard-motor-bracket-for-bracket-assembly-11887999-and-11887981--11888039?green=335548E6-0538-53D9-ABF4-7EFBCE497467&cm_sp=Onsite-Recs-_-MB-_-PDP
These reviews indicate at least 2 others with similar issues. The mechanic indicated that the old fiberglass over wood is much better design because when the plastic goes it goes all at once, where the fiberglass/wood tends to fatigue by getting loose so you have time to detect it. That makes a lot of sense to me, so I think I'm going to build one myself.
Regarding alternative lighter engines, I'm hearing mixed things. Relatively consistently most folks prefer the Yamaha's, but when getting to details, most of these are using a 2 stroke (which isn't made anymore) or 2 cylinder (which gets almost as heavy as what I currently have). Per the mechanic (who might be biased toward Tohatsu's), the major distinction is less the manufacturer, but instead the fact that the newer 4 strokes have to be EPA compliant, and have very tiny jets that make them fussy and clog easily. In addition, ethanol in gas exacerbates the issues, so gas older than 1 month tends to create problems. Per him, 2 cylinders, regardless of mfg, are a bit bigger and smoother, and the 2 strokers are just way better.
Regarding horsepower needed, I found an online calculator (http://www.go-fast.com/boat_speed_predictions.htm
) that suggests that 4 HP is plenty for this boat, and the issue is in the prop (http://www.go-fast.com/Prop_Slip_Calculator.htm
). Basically, I think most props are designed for very different purpose than we need. Even with a very low pitch prop, at high RPM we are just slipping the prop a lot and wasting gas. So I think what I want is the biggest low pitch prop I can find. Unfortunately, thats where I'm stuck with the Yamaha vs Sailpro issue.
In the 60#, single cylinder options, I found a Yamaha at dealer nearby that has a 4hp that looks much less expensive (http://www.clewsboats.com/#!new-outboards/c1m0y
), and I sense that its a better engine but then I'd need a better prop, and I'm having trouble finding a high thrust (large dia, low pitch) prop to match this engine. The Sailpro has a 6in pitch, 8.3"dia prop standard, and the 25in shaft for a bit more depth which I like, but some reports that the engine might be more fussy/noisy, and it currently looks to be more expensive. Or, I could try go with a heavier 2 cyl, but then I'd likely keep I have, get a better prop, and try to arrange quick disconnects.
So your opinions/suggestions.
1) Where might I find a large dia/low pitch prop for a newer Yamaha?
2) Any experience with the Yamaha F4/F6 in particular suggest its better than the Sailpro 6HP? Or is it just the name Yamaha, tends to be better 'in general'.
3) How much difference does the 25in shaft make?
4) Know of anybody selling an older 2 stroke Yamaha/Suzuki in the 60# range? (and where can I get a good prop for that?)