|Welded in prop tube|
|Somehow welding in the prop tube took all day, along with welding back in the cutouts over the hull cooling unit.|
|First we had to line up the
engine again (above) and make sure it was centered. Then
we placed the prop tube as far as it was previously
marked and welded on the lower half of the plates. After
the tube was spun around, the shaft was inserted on it's
cutless bearings and the whole thing lined up using
We already know the engines angle is correct because of the laser sighting we did several days back.
In the photo to the right, you can see the small plates I cut out for each frame the tube passes through. If there is a slight error, the position on the engine can be changed by 1/4" or so fore/aft/ port/star and over an inch vertically.
Also, it is very likely that we won't even be using the bearing at the engine as with the shaft size and length, 1.5" x <7' aquamet SS the wobble will be minimal at 1000 RPM max.(2.7:1 ratio =2700 engine RPM)
If the RPM was lower, more stabilization would be needed.
Tube in at last!!
|Another bonus (
after much research on Gena's part ) is this will allow
for more engine movement, thus we can keep our softer
mounts and less hull vibration and less noise!
With longer / thinner shafts, a bearing fore is required, even one more to center to stop flexing in the shaft at high loads/ low RPM . Therefore a careful consideration must be taken even in choice of design of the boat.
|Once everything looked good, Gena welded up the
plates. The frame immediatly aft of the engine is to be a
sealed bulkhead, so it was important to achieve a good
The extreme aft of the keel cannot be used for trim ballast ( adding once in the water ) because the shaft only left about 3/8" each side at the widest. Ballast should be in the bottom of the keel!
So we have to decided what we should put in there instead. A sealed airspace is not a good idea in the keel, especially when no coating can be applied under the shaft. If water ever got in there it would cause major damage over the long term.
Filling it with tar or oil is probably the best solution, but that's a lot of cubic inches to fill!
Pour in foam may be another solution. None the less, we can't weld on the cover until we decide.
6 hours - Fit plates on to prop tube and mounted in place