Need a Dimension on a Speedmaster 21-1/4" Hydro Strut

[TRUCKPULL]

Here's a pic of the 3/-6" strut with the 5/16" OD C'bore in there... The seal is off to the side, resting on the bottom of the boat, by the water lines. This is the first iteration, I used a small aluminum plate as a seal retainer. I'm going to do a circlip next..

Craig
I have a question?
In your picture - why is your strut so deep?
Bottom of the strut should be about 1/4" plus the depth of the sponson bottom from the bottom of the hull.

By looking at your picture, the strut is down way past that, the unsharpened portion is showing down past the bottom of the hull.

What type of prop do you run on that hull ( submerged ) ?

Larry

[CraigP]

Early pic, I was seeing how much adjustment range I had. Here's a pic today. The strut is the depth of the sponsons. The prop is a Octura 1742/3 blade. I run M445, M545 and M645 as well. I added about 0.20" to the sponson depth when I redid the sponson bottoms. That little bit of unsharpened strut is only in the water taking off from the shore. Boat rides nice right on the prop, like a hydro should.

[CraigP]

Actually, there's not much difference between the two shots... This boat has hit 62, never blown over, so I'm pretty sure the setup is fairly good.

[CraigP]

Here's the sponsons. This boat is very aero light stock and has a bad case of the sponson dance! I flattened the very high angles, placed in a water stiction break and increased the overall depth of the sponsons. What this did is increase the area for the air to escape back behind the sponsons, thus dumping the air buildup it has in stock configuration. My numbers told me this wasn't quite enough, so I made and installed a reverse wing in the front. Under normal water conditions, it diverts some air from the bottom to over the top of the boat. If the nose comes up due to wind or waves, it exposes more of the reverse wing, creating negative lift and bringing it back down. The system works good! It has been pointed out by others that the delta sections on the front of the air trap (referred to as "armpits" by one person) is the reason for excess air under the boat, and I concur. The wing really offsets the ability of that hull feature to grab air.