Jackplate on tunnel hull

[mildot1]

Installing a CMC hyd jack plate,5 1/2" set back on my alumacraft 1650 tunnel hull.<br />Looking for guideline of where cavitation plate should be in relationship to bottom of boat??? I am guessing that it could be higher than boat bottom??<br />Tunnel is fairly deep(6" plus) and I want to be able to raise the motor as high as possible for shallow running.<br />I will add low water pickup if necessary.<br /><br />Thanks<br />Brad

 

[Mark42]

Re: Jackplate on tunnel hull

I think if the prop gets too high up it will suck air from above. I would start at a height that would be typical for a non-tunnel hull, see how it performs. Then raise with the jack plate until it stops performing well?<br /><br />Maybe some tunnel hull people who converted to outboard can help you better.

 

[Dhadley]

Re: Jackplate on tunnel hull

Your final X dimension (height) will depend largely on your prop. Rule of thumb -- for every 5" you go back you can go up 1".<br /><br />If we were doing it we would start with the plate about even with the roof of the tunnel with the plate all the way down. The plate should mount in the existing holes and then you can set the motor on the plate anywhere you want. <br /><br />A water pressure gauge is a must!!<br /><br />If you dont have one, get one. Run the boat as is, without the plate to establish the baseline water pressure.