I am replacing the plywood in the bottom of a 18 foot fiberglass boat how do you attach it to the bottom?

Question

do you use screws or rossume

Answer 1

You need to use exterior grade plywood. Attach it to the bottom with waterproof glue. After the plywood is down, then fiberglass over it. Make certain that all of the plywood is covered with fiberglass.

Regards,

Dan

Answer 2

I have done a couple of these jobs. I like to use liquid nails outdoor construstion glue. Then use drywall screws. Be careful how long the screws are especially near the sides of the boat where the outside of the boat is close to the bottom. Also be sure not to put a s***w in your gas tank. Be sure to use pressure treated wood as well. Good luck.

Answer 3

Many recommend that you fiberglass the top and bottom of each sheet of plywood you have cut to fit for your boat floor.  Then with the drawing data and measurements you have of the stringer positions, secure each one with an appropriate sized wood s***w on the stringers and seal EACH s***w hole with silicone or appropriate marine sealant before permeantly putting the s***w in.

I cannot stress the importance of sealing any holes you drill in your boat, failure to do this will mean a repeat of repairing boat floor or worse.

After all of the fiberglassed plywood sections are installed, you need to put a layer of fiberglass over the entire floor to cover all of the floor and seal any gaps left by the plywood or sides on the floor.

Get a book on boat floor replacement if you are unsure on this and don't just take my word for it, research and verify first.

Make sure you are doing the installation steps correctly, failure to do it correctly can result in having to redo it, transom damage, or a permenantly damaged and unsafe boat.

Answer 4

Here's the deal- if you use marine grade plywood, it is not necessary to fiberglass it, just s***w it in, but be sure and s***w it into the stringers that the old sheet of plywood is attached to- be sure and use brass or some type of s***w that will not rust when exposed to moisture- dry wall screws will not last when used in a boat. when you get it secured with the screws, it will be ready to carpet-use marine grade carpet for this also, and if you do it this way, you will not have to redo it for years and years, if ever. Good luck!

Answer 5

I would not recomand drilling holes trough the hull and never use regular silicone sealant on polyester.

Make sure that the hull is not twisted when you glue in the new floor and that the hull is supported flat otherwise you`ll be making turns only :), fill the gaps with some kitty hair or rolls of fibers with resin and never use resin allone to fill gaps as it will crack.

Better not use pressure treated plywood but exterior or better marine plywood but this costs some more.

Like already sayd in the above posts, coat both sides with a mix of resin and accetone 50:50 so it penetrates deep in to the plywood.

Roughen up the hull with a grinder so the resin mix penetrates into the hull fibers. Place the new floor between rakes in a bed of resin mix with fibers all around and s***w it to the stringer with stainless screws and glue the sides to the hull.

Use some 8-10" strokes on the edges all around the new floor to the hull and after cover the whole floor with a layer of mat.

An other more important thing... How is the transome??

If here is anny rot or week spots you better replace it now while you are on it or you have to do this again later.

Itchy job, but after half an hour inhaling resin you don`t care!  

A good book can be : runabout renovation by Jim Anderson

Frank,