Building a Livewell plug/mold Newb questions.

[SamCar254]

Good morning,

I am looking to build a plug/mold for a leaning post livewell for my Mako 254. There are aftermarket options available but I feel the quality to price is lacking.

Would making a plug from plywood or mdf be ok?
Could I make a single piece mold, popping it out from the bottom suffice or would I be better off trying to make a two-piece mold splitting it width wise along the center? I will provide a couple pictures of what I am trying to accomplish. Any information would be appreciated.

 

[Blueknarr]

Welcome to the forum.

Molds are excessive. Plug to mold to product--doubly so. Your expense: quality ratio is likely to be worse than the off the shelf options.

Live wells benifit from insulation. Why not start with core foam. Mock up and adjustment of elements is quick easy and relitively cheap. Them cover in glass and resin.

Good luck

 

[SamCar254]

Welcome to the forum.

Molds are excessive. Plug to mold to product--doubly so. Your expense: quality ratio is likely to be worse than the off the shelf options.

Live wells benifit from insulation. Why not start with core foam. Mock up and adjustment of elements is quick easy and relitively cheap. Them cover in glass and resin.

Good luck

Thank you for taking the time to reply and give some insight. Are you suggesting that I just build the unit out of a foam material and then coat it with glass and fairing compound? Forgive the stupid questions as I am a novice here and am trying to learn. If I did build it out of foam first I think it would be a little difficult to account for how thick the glass layers would be upon completion or am I way off in this thinking? Thanks!

 

[Blueknarr]

Yes. Foam first then cover with fiberglass.

Yes. Estimating glass thickness can be tricky. Most fiberglass cloths are predictable. If in doubt make it slightly smaller and make up the difference with fairing.

Depending on construction details, there could be advantage to glassing one or both sides of the foam prior to assembly.

 

[SamCar254]

Yes. Foam first then cover with fiberglass.

Yes. Estimating glass thickness can be tricky. Most fiberglass cloths are predictable. If in doubt make it slightly smaller and make up the difference with fairing.

Depending on construction details, there could be advantage to glassing one or both sides of the foam prior to assembly.

Thank you for the tips I will look into that. I was just looking at some of the ones on new boats and it seems the fiberglass is extremely thick 1/4-3/8 thick in places. Do you think foam cored glass will be just as durable? How many layers would you suggest. It will have rod holders and a grab rail attached to it.

 

[Blueknarr]

Depends. Overall wall thickness will definitely increase by the thickness of foam. The combined thickness of the glass in the sandwiches is thinner than in un-cored solid.

Not all fabrics have equal stiffness per thickness. CSM usually requires greater thickness to equal woven fabrics.

 

[SamCar254]

Building a Center Console - Plans - Page 2 - The Hull Truth - Boating and Fishing Forum https://www.thehulltruth.com/boating-how-s-kerno-memorial-forum/815909-building-center-console-plans-2.html

This is, I think, the technique you are referring to. I am assuming I would be using either .5" or 1" foam core. What would be better?

 

[Blueknarr]

It is simular. He built an undersized plug out of foam, then covered it with a second layer of foam. He then glassed the outside, removed the plug to glass the inside. It is possible to skip the plug altogether.

Thicker foam offers greater insulation. A thicker core allows thinner skins to achieve same stiffness. Thicker foam is more expensive. But so is special ordering custom thinly sliced foam. Thinner foam is easier to flex onto curves.

Advantage both ways

 

[Blueknarr]

SanCar

I'm glad you're seeking advice from multiple sources. It gives you greater perspective.

IMO cheep home center Styrofoam would be acceptable for this project. There are many here with different opinions. There are several threads discussing the pros and cons of the many foam choices. I encourage you to read a few of them.

You didn't include any dimensions for your live well. I'm assuming it will be less than 4 feet in any direction.

My approach with some explanation;

+One inch H80 foam leftover from another project. If you choose Styrofoam rember that it can't be used with polyester, and a thick glob of epoxy may produce enough heat to melt it. The pellets in Styrofoam don't shape well. 1/2 inch may need temporary support while the glasswork cures. 2 inch is more insulation but starts to cut into interior volume.

+pre glass interior face of foam with 6 oz twill. Reduces the frustration of glassing in confined spaces.

+assemble with toothpicks and masking tape on exterior.

+fillit interior corners

+Second layer of 6 oz twill overlapping joints.

+remove small sections of foam where hardware will be secured. Replace with plywood and or fairing compound.

+remove masking tape and perform final exterior shaping.

+ glass exterior with 12 oz bi-axial plus 6 oz twill or 4 layers of 6 oz twill. The extra thickness of the external glass provides extra impact protection.
+fair and paint with a catalyzed urathane

 

[kapnD]

Sam Car,
The picture shows a quite complex piece, obviously molded and mass produced, but not realistic for a first time builder.
Look for a plastic barrel that will serve as a bait tank, and build an appropriately sized plywood box around it, glass it, arrange the plumbing, then foam the tank into the box.
Keep it simple and easy, that way mistakes are less costly, and you’ll gain experience needed to build more complex pieces in the future.