Exteding a hull?

[Matt.D]

Does anyone have any info on or has done a hull extention ?
I have a 21ft fly bridge . glass over ply. want to extend it 4ft.
Thanks Matt

[kapnD]

Matt, You need to give us more information on the boat. Type of power, planing or displacement, type of use intended and speed, pictures etc. You are talking about a radical change, must proceed carefully. One thing in your favor is theat glass over ply will be easy to work with! Don

[Matt.D]

Hi Don. It will have a 225 outboard on a pod bolted to the transom, will do aprox 30 knts, its a fly bridge cruiser mainly for fishing with a v beath up front.and its a planing hull. . Ive searched the net but cant find any info or pic anywhere. Thanks Mate.

[CDK]

I've done something similar 2 years ago. Made the extension in a makeshift mold, laminated aluminium L-profile all around the inside edge and bolted the box to the existing transom after applying a layer of marine sealant (Sikaflex). In my case I needed another ft of engine room for 2 Berkeley jets, so I made holes in the old transom where I needed them, left the rest intact.
I contemplated laminating directly to the existing hull, but decided not to because I didn't trust the adherence to 25 yrs old laminate, especially the bilge that has been oily for as long as I can remember. Experts told me that it can be done, but the contact area should be 4-5 times the wall thickness.

[Matt.D]

Hi CDK, thanks for the reply. so u build an alloy extention tub and bolted it to the exsisting transom? is that correct? i want to extened my hull for extra fishing space. Matt

[CDK]

Replace "alloy' with "GRP" and you've got the picture.

[jim lee]

cdk why would you want 2 jet drives?

-jim lee

[Matt.D]

Sweet. i also want to make a pod that will double not only as a outboard mount but a deck extention 1mt long as i want to cut the transom out and extend to the floor thur to the new transom. Was thinking about making it in aluminum for extra strenght.
Matt

[CDK]

cdk why would you want 2 jet drives?

-jim lee

I surely don´t, but I didn´t know it then....
See my post on the surface drive sub/forum