JSchneider

Hello,

I've decided to take on another project and need some advice...the plan is a scratch build of a 1988 Bayliner 3818. I have some detailed drawings of the boat that are blowen up to a scale of 50 inches long and 17 inches wide. My plan, and this is where I need some help, is to carve the hull from foam. Once the hull is carved, does anyone have any advice as to what to cover it with to get a glossy finish? Several years ago I built the Dumas Donzi which has a great finish on the hull and would like to replicate that if possible. If fiberglass is recommended, does anyone have any advice as I have never done any fiberglass work in the past.

Thanks for your help.

John

Umi_Ryuzuki

First off, use an epoxy based resin for your fiberglass work.
The polyester resins will attack the foam.

Precut your fiberglass to lay nicely on the hull, then set it aside.
Coat the hull with your resin, then press and brush the fiberglass back onto hull.
Wear gloves, and use your hands to hold one area of fiberglass in place while you brush,
or use your other hand to press the fiberglass into the resin and against your foam hull.
This will help keep the fiberglass from pulling and bunching into wrinkles.

[8D]

Steve Collins

My Feedback: (8)

To give the hull a little crunch resistance, I would use two layers of heavy cloth followed by a final layer of 3/4 ounce cloth.

I was once in your shoes having never done fiberglassing. I was afraid to try it since I figured I would botch the job. Once a friend supervised my first glass job, I was left wondering what I had been afraid of! It really is a fairly easy process.

Follow Umi's advice in the above post and you stand a great chance of success.

West System epoxy is a great choice for the resin. Z-Poxy is also one that works very well. You want to choose an epoxy that is made for fiberglassing because they tend to be thinner when mixed than just a regular epoxy glue.

Many folks will advise thinning the epoxy with alcohol, usually denatured alcohol, but, in my experience, you run a risk of the epoxy curing to a rubbery like consistency instead of the hard surface you need. Both the West System and the Z-Poxy are already thin enough to do the job.

Two coats of resin over the final cloth layer (you must sand the gloss off the first coat of epoxy before applying the second coat) will fill the weave and then the entire hull can be sanded down to a nice smooth surface.

JSchneider

Thank you for the great info, I certainly appreciate it. After watching a few fiberglassing videos on youtube, it doesn't look that bad. Steve, just a couple of quick questions...when you say heavy cloth, do you mean 5oz or 6 oz cloth? Also, after the fiberglass has dried would the hull have enough strength to remove the foam inside completely and just use the fiberglass shell alone?

Now, if I can just shape the foam so it resembles a boat...

Thanks again,

John

Steve Collins

My Feedback: (8)

By heavy cloth I was referring to the 6 ounce cloth.

If you intend to remove the foam after glassing, I would recommend a third layer of the heavy cloth.

Removing the raw foam by whatever means will leave an extremely rough surface on the inside of the fiberglass hull because the epoxy will absorb into the surface of the porous foam.

To minimize this, you will need to provide a surface on the foam that is extremely smooth that fills in the porousness so that the resin does not soak into the foam. I have never done that myself so hopefully there are some videos available that can guide you.

emperorchuck

If you plan on removing the foam plug from your hull, you'll definitely need something to give you a nice surface to release from, like Steve Collins says. I've had good luck with duct tape in the past. Yes, it works fine; just make sure you layer it a bit so the tape covers all of the foam; the slight bump you get from the overlapping tape won't show after a couple layers of cloth, and the plug pulls out cleanly leaving a nice clean inner surface.

Also, make sure you control the temperature of the area you're working in; no working in direct sunlight or that sort of thing...

rmdesignworks

hey guys,

i thought id throw another way of glassing,,out there, i made a tug hull with this format and it worked well and gave me a very strong hull with very smooth surfaces....and the hull exterior is not affected by water or most chemicals

supplies: hull plug, aluminum foil, superglue (fast set),2+ rolls of self adhesive white or yellow drywall repair tape, 1 or more packages of the large tubes of JB WELD "5 ounce size", some type of stiff yet flexible spreaders/squeeges, scissors, epoxy or resin compound, fiberglass mat or cloth


1 form your hull to desired deck dimensions
2 cover with aluminum foil
3 apply self adhesive drywall repair tape to foil surface. applying more than one layer of tape over itself in different directions gives a very strong weave. someitmes the tape doesnt want to stick to itsel so a little super glue in those spots will remedy this "lifting"
4 mix JB WELD (one package to start coverage will very by size of model and thickness of application)
5 apply JB WELD over tape and press into tape (this stuff is very sandable so dont worry about sags or drips at edges)
6 this outer shell, the JB WELD should be formed using more JB WELD or putty/filler before removing plug, at this point the hull is flexy
7 when satisfied with hull exterior remove plug completely and all aluminum foil,it should peel out relativly easy, i pin my sheets of foam so they can be more easily seperated. if you glue them together you will have to break the foam out. note see step 10
8 with plug removed mix epoxy/resin compound and using "yellow tape" apply first run of epoxy to the keel and bow/transom areas
9 using fiberglass cloth/mat glass entire hull interior cross bracing can be added at this point as well as deck cleats
10 trim hull edge (bulwark) to desired depth using dremel,,you can trim hull edge before removing plug