GOP Home Build

Foredeck sealed.

Started the big step of sealing the foredeck.

 

Update

More hull work, added Chines and sealed forward Gunwales.

 

In hindsight with the amount of work you done, would you say it was even worth it to use donor hulls?

 

Hehe no!! This thing just became bigger and bigger as it went on. The donor hulls were a waste of time, but they got me started I suppose.
The next build will be from scratch.

 

Yeah it looked like they set you back more than anything! But as you said it got the project going.

 

Indeed, I have learned a lot and made a lot of mistakes with this build. Great thing about fibreglass is you can always grind or sand it and start over, if you have the energy.

 

What should be the safe clearance from waterline to transom top?
The Draft unladen is 400mm. When I stand on the boarding platform between the motors it goes to 500mm. Tunnel clearance aft is 150mm.

As can be seen in the image, the top outboard holes never get wet, even with no bow weight and me standing at the rear of the boarding platform.

 

Side view with waterline marks

 

Are they XL shaft (25") ? No problems if so.

 

No, 20".

 

Really ? The swivel bracket looks short on the Honda. Unless you are venturing onto rough water, you should be alright, but don't have it any deeper than around 450mm if you can do it.

 

450 draft?

 

Hull only draft. The old 18' Shark Cats with the 70 hp 20" engines were at least 450mm hull draft, a few engines got drowned, but they were subjected to a lot of offshore fishing in lumpy conditions. Most 16' cats used 20" leg engines because they could not get 25" in less than 85-90 hp. Should be OK, and better if you can get more weight forward.

 

Sweet thanks. Once more weight up front, I hope the draft to be under 400 hull only.

 

Ventilation Issues

I dumped her in the lake again this weekend after removing the centre pod.
I also lowered the motors and am still getting vent issues. The AV plate is runnning at water level whilst underway. The hull is riding perfectly and eats up the chop with no sneezing and seems to be very dry and notably smooth in a choppy lake. I'm really really happy with the way she rides.

Having "roughened" the hull using a sandpaper like finish is the first thing that comes to mind. In my attempts to fracture the laminar friction, could this be producing mass cavitation from the hull and providing to much aerated water around the prop? Almost like getting cavitation in a foamy sea?

What might my best options be from here? Four blade propeller, lowering the motor (although the vent plate seems perfect, smoothing the hull( lots of grinding and fairing) or changing the outboards to XL's ( very costly as Honda don't make an extension kit for these motors.