Not about motors....but, how about some input on my foam flotation project for the Stamas?

Howdy Gang.....on my other thread I'm continuing the progress of the Honda refit for my Stamas. Right now I could use some feedback on the foam I'm about to put under the motor bracket.

I can get the whole 7 cu ft under the center of the bracket, out to 17" either side of the centerline. But I'm wondering if I should spread it out instead of putting all of it directly aft under the center of the boat. My concern is......will this make the boat roll-y, because there would be no lift to the sides?

That amount of foam will provide lift under the centerline, but no lift under the "wings" of the bracket. Would that make it "tipsy"?

In the picture the down legs indicate the outside limits of the foam, if only under the middle.

I'm thinking I should put 4 cu ft under the centerline, and 1.5 cu ft under each wing, to even the lift, and therefore dampen the roll.

Does this make sense?

The reason I ask is because it would be easier to put all of it under the middle than to split it 3-ways. Just a little more work.

Your pics are not real clear but it looks to me like the motors are sitting too low into the water. Is that a custom made jack plate? You want the cavitation plates abut 1/2 inch under water on a full plane. With the distance from the transom to the gearbox you could probably put the cavitation plates up 1/2 or 1 inch above the bottom of the transom. When on a plane that foam will have little effect you can add trim tabs and give it some lift and bring the bow down?

If I were in your position I would spread it out laterally as much as possible.

I also think that trim tabs would be a good idea - the bigger the better. I've had good luck with the electric Lenco's.

chawk_man said:

If I were in your position I would spread it out laterally as much as possible.

I also think that trim tabs would be a good idea - the bigger the better. I've had good luck with the electric Lenco's.

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Trim tabs have bottom paint on them. That's why u can't see them. I'm thinking lateral is better as well.

motors are way too low, agree with spreading the foam.

crankbait said:

motors are way too low, agree with spreading the foam.

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Actually, with a full load of fuel, etc, the exhaust ports are a solid 8" above WL. With the foam, I'm hoping to raise the stern 3", so I'll be at 11".

The pic doesn't show the setup well.

The cavitation plates are 2.5" higher than the bottom of the hull, as measured with a straight edge. The bracket is 30" deep (from transom to back edge), so you add 1" of height for each foot away from the transom. Hence, 2.5" higher than the hull for the cavitation plates.

What if you made a tub out of fiberglass and glassed it in to the whole underside with a drain plug? Thats similar to the armstrong bracket's design, except armstrong is aluminum. If your exhaust ports are 8" above waterline, what is the reason for bracket?

Skooter said:

If your exhaust ports are 8" above waterline, what is the reason for bracket?

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You mean, what is the reason for the foam? See the pic. The boat is really stern heavy.

The foam isn't for raising the motors. It's for leveling the boat. The fact that the motors will be even higher in the water doesn't matter. The only thing that matters is the relative position of the cavitation plates to the bottom of the hull. That doesn't change by raising the stern. That relationship is fixed.

The reason the motors can be so high on this boat is because it is a modified vee, as opposed to a deep vee. If it were a deep vee, the motors would have been mounted lower.

Oh, and glassing in the underside is more problematic than attaching foam blocks. Believe me, I've studied the situation.

I'm going to pour the foam into a deep SS sink I have (heavily waxed of course). From there I'll cut into forms to fit, coat them with epoxy, and then thru-bolt them to the bottom of the bracket. They'll be removable and have the same black bottom paint.

In that case big ass trim tabs should do it

Skooter said:

In that case big ass trim tabs should do it

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Well, at speed on plane, yes. The boat has tabs. But at a stop or idling the cockpit is like walking uphill. It has to be fixed.

I gotcha now..sorry, I should've gone back to re-read post..keep us informed on how it works out. Also, not sure where your fuel tank is located, but it may play a role in it also.

I'm in the garden products business, so it will be awhile before I have the time to work on this. But I'll update with pics as I can. It's an interesting project.

I don't think it will make it "tipsy" by putting the foam right under where the weight is. The extra floatation is needed because of the extra weight of the 4 strokes over the 2 strokes that were on the boat. So that weight is near the center line of the boat. now if your were adding 2000 lbs of floatation in the same place, yes you would have an issue

Just tuck it inside the two main braces, and make sure there is no place on the leading edge (closest to the transom) for the water to grab onto while you come up on plane (or come off plane).

And as I mentioned on your other thread, use closed cell foam. Water always seems to find a way into open cell foam....... even after being enclosed. Had to replace a floor and stringers because Searay used open cell foam in my old boat.