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It is not a performance boat (average performance commuter boat?), but it is relatively light compare to larger fishing boats and pontoons that this motor was likely designed for..

I want to keep the prop submerged for this one.

Just wish I could trade some of that low end toque for more power at the top.

Overall though the boat is better this way than the Yammi 50. Revs are lower due to gearing and 15" vs 14" prop, and it is quieter, and it gets up on plane with less effort. I think I was expecting more top speed, but I'll curb my expectations.

Theoretical top speed with your 15' is 48 mph at 5500 rpm with zero prop slip.
Consider 10% slip (likely more with a modest hull) and you're at 43 which is about right.

Best we've managed with a 20" Mertens cleaver running balls out on the Thunder Cat was 62 mph which equates to 4% slip.
That's exceptional and a really scary ride.

I trust you are running premium fuel (Shell 91) and good oil. Ours runs like a dog on anything else.

I'm seeing max 71 or 72km/h max (44.5mph) trim way high (but not venting the prop), light load. Prop slip was approx 5% when I did the math.

Fuel is what is available locally (89 octane no ethanol). Oil is Merc or Yamalube. I did rebuild the carbs and added Chris Carson reeds over the winter. Compression was equal across the 3 cyls at 120psi on my cheap gauge when I checked it before purchasing the motor used.

Absolutely nothing wrong with those numbers and she's a good looking little ride.
Everyone needs a utility boat (something I'm looking for).

Yamaha's are fairly neutral props compared to Choppers which have natural bow lift.
Merc Trophy 4 blade would be somewhere in the middle
If you get a chance to try one or the other you may notice less need for trim but there's nothing wrong with what you have now.

From The Practical to The Ridiculous...

Nice, yeah, that looks quick.

How rare are these Mercs as short shafts? I've only seen one online (in Mariner form).

Very rare, mine started life as a long shaft.
Converted by previous owner using a 40 hp parts.
The tiller was the hardest part.

Ya...I was off on my models. I was thinking of the 49cu...which interestingly enough I have mine on the same boat lol.

Is that a Cutter or Peterborough?
Know I've seen em before but...?
I need a beater.

Mine is a Thundercraft Playmate v142. I've also seen copies branded as Peterborough. I'd be surprised if anyone found a dry and solid one. They weren't built well and didn't keep their cheap plywood transom/stringers/floor dry.. I think it is an excellent boat though in terms of size and weight, and utility.

I believe Originally they were Glastron design, also model v142.
http://www.classicglastron.com/68gl-v142-153-web.html

check out the resto mod on this one:
http://www.screamandfly.com/showthread. ... ost2373469