motor mounting hight

[jl_photo]

i have a 14 foot bayskiff. looks identical to a flat bottom carolina skiff except it has a 4 deep inch tunnel. (tunnel starts about 24 inches from stern)


where should the cavitation plate be in relation to the tunnel or the bottom of the boat?

I have had some people suggest that it should be even with the bottom of the boat, ignoring the tunnel, and some saying it should be at the top of the tunnel.


I have a 40 yamaha with tilt/trim and a stainless prop.

I want to go fast and be able to go in shallow water.

i also have a 20 foot shrimp net I intend to pull.

will I need to enlarge the cavitation plate?


.

 

[Dhadley]

Re: motor mounting hight

The plate should be no lower than the roof of the tunnel. If it has to be lower than that you're defeating the purpose of the tunnel. Depending on your prop design you may or may not experience venting. Most likely you will. Some of the boat builders have come up with their own version of the fin we designed. It's rather large but that's why it works so well. It'll "capture" the water that's normally lost as it goes past the gearcase. Talk to your boat builder.

 

[jl_photo]

Re: motor mounting hight

Thanks for your reply,

my boat was built by bayskiff who seems to be out of business. i don't think i can get any help from them.

i see a lot of anti-ventilation plates ranging from a dol-fin to a large custom plate like the ones on a shallow sport .

how much plate do I need?

 

[Dhadley]

Re: motor mounting hight

How much you need will depend on what prop you're using and testing on your hull. I'd guess that one that starts at - or as close to - the front as possible, angles out as it goes back so it extends out past the prop diameter, and goes past the rear of the AV plate by a couple inches.