On Fri, 28 Oct 2011 12:45:28 -0700, "Bruce L. Bergman (munged human
readable)" wrote:
On Fri, 28 Oct 2011 14:12:35 +0700, John B.
wrote:
On Thu, 27 Oct 2011 21:33:58 +0000 (UTC), wrote:
Greetings Bruce,
If only I had a dock. Everywhere I launch the boat is from a ramp. So
I need to get the motor on and off while the boat is on the trailer. I
suppose I could build some sort of crane on the trailer. Takes the fun
out of building an inboard though. And doesn't address the noise. And
I would need to get a smokin' deal on a 4 stroke outboard. But at
least for now I could use the trailer mounted davit to put the Merc
on.
Cheers,
Eric
Seriously, can't you just leave the motor on the boat and trailer it
that way? Maybe make a hoist/engine stand on wheels for removing the
engine at home if you need to do maintenance on either the engine or
boat? Certainly the blokes with the three 150 H.P. outboards on the
back don't take the engines off to trailer the boat and I used to see
a lot of "fishing boats" with 5 HP outboards being trailered.
Sure, building a spiffy liquid cooled engine and all the fixins would
be fun but I'll bet that either, A. It won't be very serviceable, or
B. it will take a lot longer then you estimate to finish it.
I just had a look at small liquid cooled Komatsu diesels - all in the
115 lb. dry weight range. An air cooled engine initially seems lighter
but adding water cooling, water cooled manifold (although not strictly
necessary) and this and that may raise the weight to about the same as
the diesel. An air cooled engine with a water cooled exhaust with an
add on pump to supply the water would be the lightest and noisiest.
The air cooled engine would also be the hottest but as a liquid cooled
engine is running at about 200 deg. (F) it will burn almost as well as
the air cooled :-)
Nope, my suggestion is to leave the motor on the boat. If you feel it
hangs down too far to trailer then you could fit the sort of
retracting engine mount that they use on small sailboats that use
outboards for auxiliary power - Richard (cavelamb) can probably
describe them if he is reading this thread.
Nope, like the day job, I wouldn't throw the outboard away until I had
actually built, tested, rebuilt and made the revisions for the air
cooled motor design :-)
Well, there are a few angles to this. Beginning with the boat being
rated for a 10-HP outboard, but you can throw all the ratings out the
window when you start cutting holes for a shaft stuffing box and
through-hull fittings for cooling and return lines, and making an
inboard out of it. How are you at TIG Welding to put the engine
cradle in?
Any hole in the hull is a potential sinking-at-sea leak, and a
homebrew inboard rig has lots of failure modes - and an aluminum hull
only magnifies that, the prop gets badly out of balance and you have
to keep pressing on towards shore, you'll have fatigue cracks
springing up everywhere in the hull...
Even with a life preserver and the typical small-boat survival gear
are you in good enough shape to survive an extended stay in the drink?
Old Farts in bad shape... Not Sayin', Just Sayin'...
KISS - If you want an inboard, build or buy a hull made for it. This
is a Life Safety thing you shouldn't take lightly.
Or go to a local Marine Architect with your plans and drawings and
have him sign off that the plan is sound - or engineer a proper
solution that won't send your little aluminum skiff to the bottom with
all souls on board.
Otherwise I'd go get your dream quiet 4-stroke outboard and leave it
mounted on the boat while you trailer it, it should be just fine.
Or put a Davit Hoist on the rear of the trailer, the Harbor Freight
37555 is perfect, just get a longer piece of pipe to weld it to the
trailer chassis in the corner. Oh, and spritz the jack cylinder and
winch every time with LPS so the rust worms don't get it.
But now that you have the engine off the boat and on a dolly at the
Marina, you have to wrestle the engine in and out of the car trunk or
truck bed... Why?
If you think that rough dirt roads are going to make the weight of a
10-HP outboard wreck the transom and fall off on the road, add extra
bunker rollers/pads at the back of the trailer to support the transom
better.
And you can always get bigger cushier tires for the trailer to cut
down on the shocks - instead of 4.80X8 tires at 60 PSI you get the 10"
wide flotation tires off a Tent Trailer (215-60/8 AKA 18.5-8.50/8) and
drop them to 20 PSI. Swap the fenders, and they'll fit.
-- Bruce --
I put a 4 horse 4 stroke on our 14' jon boat. Trailer has 12" tires.
I leave the motor in place and launch off a ramp. I expect it to
outlast us.
2 hp would have been fine since we're not going to plane and power
past that required for hull speed is wasted. I found the 4 hp lugs
and just generates more wake above 1/2 throttle. Everything seems
much happier at 1/2 throttle or below. To plane my wife and I would
take 15 hp. I don't think a 9.9 would do it. Fuel consumption is
miserly. Our other boat is a 22' Pathfinder with a 150 Yamaha down at
the coast. Not so miserly.
The jon boat's good points are it's cheap and will take a beating. Bad
points are it's not an efficient hull for displacement speeds, and
aluminum doesn't absorb vibration. Maybe I'll build a plywood boat
some day (different forum).
Be aware that current 4 strokes smaller than 8 hp are single cylinder.
Much more vibration than the 3 hp 2 cyl 2 stroke Evinrude I ran 40
years ago.
Pete Keillor