13 Riverhawk- a few fiberglass ?'s

I would imagine the bench seats do not have any wood backing in them, they are likely foam blocks glassed into the hull for level flotation pruposes. Mounting anything substantial to them might not be the best idea.

the best option you might have is to add the mounting pad outside of the bench, by glueing a wood pad on, then laying some glass cloth over the top. I say cloth because I would recommend epoxy over polyester or vinylester resins, but that is my new personal preference.

If you use epoxy, stay away from the chopped strand mat materials. they are bound together with a light resin that relies on the styrene in polyester resin to break it down. Epoxies don't have this styrene, and will produce a weaker laminate. Chopped strand mat is generally structurally weaker than cloth whatever the resin you choose.

 

You can always add back the chopped mat texture after the repair or addition if you use cloth. By cutting up a small bit of cloth into strands, and scattering them onto the outermost layer of cloth or even into wet resin after the cloth laminate has cured, you will end up with a similar texture, just not utilizing the mat material.

There is nothing wrong with using polyester resin and mat though, I've used it for years, and almost every boat built today uses polyester or vinylester resins. That's not to say they are the best by eny means, but are less expensive. They don't make for as good a glue material as epoxy though.

 

Epoxy is roughly $100/gallon, some more, some less. Polyester is $25-30/gallon.

Most polyester resin repairs fail because of poor surface prep. Applying polyester resin on to properly repaired polyester laminates is perfectly fine.

That being said, I would much rather work with epoxy resin. It's nearly odorless, wets out clear, and is really a joy to work with. It does just what you want it to do for you.

Cured epoxy resin is waterproof. Cured polyester resin is not, it will absorb water over time and delaminate. This might be another reason you see failed repairs with polyester resin. If not covered with gelcoat or a good waterproof paint, moisture absorbed will cause the delamination, or flaking off of the repair area.

As for your crack repair, that's relatively easy one, here's a highlight

http://www.westsystem.com/ss/repairing-fiberglass-laminates/

 

give riverhawk a call and ask for Paul----he will be able to answer ur questions---been there for yrs
riverhawkboats.com

k

 

Cardboard works good for templates, you can also use scrap plywood to play with different designs, shapes, etc.

Epoxy is more expensive, but having worked with both, I'd spend the money.

The wood depends on what you want to use it for really. A base to mount a seat pedestal too, you could use 1/2 B/C ply from a big box store with no problem.

Here's another advantage to epoxy over polyester resins. Epoxy will actually penetrate the wood fibers, providing a vastly superior structural bond to it, and water proofing the wood at the same time. Polyester resin will mechanically bond to the wood surface only. It really depends how strong and how long you want it to last.

The project needs to fit your budget too. Only being able to finish 1/2 of it doesn't do you any good.

 

Plywood for seat supports and backing pads...
try pressure treated plywood, you know they'll end up wet.

http://www.naturalhandyman.com/iip/infxtra/infpre.html

Cardboard and tape for templates.

 

I have a Riverhawk 15' original. The previous owner towed it without a transom saver and caused some damage. I used the standard fiberglass kit from Advanced Auto Parts and it worked great. I like the looks of your jack plate (please make me one).  The seats have no wood in them only foam. I used toggle bolts for the seats, after the factory fasteners failed. I have built a homemade trolling motor mount for the front (looks like a battering ram). I will send you some pictures.

TMc

 

I had a low budget idea for you to try out the epoxy, but not make a big investment.

The bateau.com guys offer a sample kit for $25 that would be plenty to do a small repair or small project like adding a seat base. That way you can see how easy and enjoyable it is working with epoxy, get a portion of your project done, and not invest a bunch of money in the boat.

Incs glass cloth, wood flour, cups, stir sticks, and epoxy, all in one.



http://boatbuildercentral.com/proddetail.php?prod=E_try

 

Take a look at my project in teh bragging spot forum, The Sawdust Skiff. All the work I've done so far has used about 3 qts.

A little bit goes a long way in my experience.