High Thrust Motors on Tunnel Hulls

[jacquesmm]

Thanks for the video, Cali. I remember seeing that one a while back. Thanks for the comment also, it helps a lot, but raises now more questions.
The Xf20 study plans show the tunnel making more of a wave, than what Cali's video shows.

That is just to illustrate the principle.

I think this is likely due to his light/ weight trimmed forward design. While it looks like it performs well, and he recommends as little set back as possible, I wonder how other xf tunnels, with more weight aft are performing. Some of the other center console, heavier versions. I also wonder how the same tunnel will perform differently, all together in a Gf18. Will the draft differences between the two hulls have any effect? I would like to pick the right jack plate, the first time. My lack of experience here, is obvious. Thanks for any input.

The setback will vary with the speed. 6" should be the average but let's consider the XF an experimental boat, rely on the reports from the other builders for the set back. With an hydraulic jack plate, you can always adjust height inf function of speed and set back but I can not predict where the apex of the hump will be better than that, sorry.

[snookiehunter]

Thanks for the reply.
So it looks like I'll go with the 4" set back. My motor showed up today, and after some measurements, I don't think I can raise it 4", before the top water intake hole is out of the water. I may mount the motor on the boat, to get a better idea, before I order the jack plate.