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Old 06-17-2013
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Practice deck core layups?

Hi all-

Bought a new boat and have looming deck core replacement. I'm a total rookie when it comes to fiberglass and was considering doing some practice layups so that my first exposure to glass work is not when I have a huge hole in my deck.

I was thinking about building a cardboard tray to roughly approximate the lower skin of the cleaned out deck section, and then doing the plywood/resin/top skin buildup. Maybe even fair and paint the top.

Would this be time well spent?

--Skagit out.
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Old 06-17-2013
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Re: Practice deck core layups?

I could never understand why anyone would use something prone to rot for cores, when foam is inert, with zero chance of rot. Where's the logic in stuff like balsa core?
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Re: Practice deck core layups?

Amen to that Brent. Is foam structurally equivalent to balsa or plywood? I'm game for a no-rot substitute.

--Skagit out
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Old 06-17-2013
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Re: Practice deck core layups?

Skagit, a trial board is a good idea- the time and material you expend learning how to do it OFF the boat will save you more time and money when you do it ON the boat.
The problem isn't the coring material, it is water intrusion.
Balsa is a GOOD core material specifically because it retains good compression strength even when/if it gets wet, but there are some arguably BETTER core materials- like corecell. But prepare for sticker shock when you price Corecell, and ask yourself whether you might just be better off properly potting and isolating all of the deck penetrations to keep moisture out of the core.
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Old 06-17-2013
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Re: Practice deck core layups?

Balsa may be a good core material but it is still wood and WILL ROT when it gets wet.
I went through a re-core of my port side decks a month or two ago as the Balsa core was completely mush in some spots.
I decided to use this honeycomb polypropylene core which costs about the same as marine ply: honeycomb at Express Composites, Inc.
Some of the other cores I priced were way expensive but this stuff worked out great; easy to cut with a razor, less epoxy usage, compressive strength.
Here is my write up (w/pics) of my re-core project: 2013, May 2nd. Re-core work party. | Odalisque

If you are unfamiliar with using epoxy I do recommend that you play with it first. I do not think you need to do a mock re-core project though; just some simple lamination using epoxy and cloth. Your mock re-core idea will not really help you with the actual job as doing the work on your boat will be quite different than anything you do on a work bench.

I'd also strongly suggest that you do NOT use plywood for your core material. It will rot pdq and for about the same price the honeycomb core material is a bargain.

Good luck.
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Re: Practice deck core layups?

Now we're talkin'...nice work Caleb. It's nice to see someone else that had to pull the whole side of their boat apart.

Thanks for the lead on the polypro core.
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Old 06-17-2013
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Re: Practice deck core layups?

I'd do a lot of reading before starting even sample work. The West book is well worth the cost but the basic info you need is available on their web site.

If you have no glass experience, I'd start with test samples using polyester resin - it's a LOT cheaper than epoxy. The "workmanship" techniques are the same. After you get comfortable wetting out fabric, rolling the glass and squeegeeing you can lay up an epoxy test so you can see the viscosity differences, cure rate differences etc. Then start cutting your boat.

I'd definitely investigate that honeycomb Caleb mentioned - cheaper than even balsa. If you need "hard spots" for under hardware, used solid glass - don't use plywood. You can buy G10 sheet in various thicknesses and use it like core where necessary.

Hunt around for industrial type suppliers - ask around boatyards and marinas etc. There is no need to pay WM type retail for the materials and you can save big $$ by buying from industrial suppliers.

Don't be intimidated - there is nothing magic about glass work. If you can wallpaper you can fiberglass and if you can make a peanut butter sandwich you can lay up cored laminations. Basic fiberglass work is classified as semi-skilled labour.

Remember to protect your skin and work neatly - grinding cured glass is to be minimized - it can't be eliminated. Micro fiber cloths and a loofah sponge are the best things to scrub the itch away in the shower after a days glass work.

Finally, enjoy yourself - it's itchy, messy work but it can also be very satisfying when you see the improvement in your boat and you'll have the skills for a lifetime of sailboats.
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Old 06-17-2013
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Practice deck core layups?

Back in 2003 i restored and completely recored a 17' Hydrostream Speedboat using a a composite product called Klegcell to replace the rotted balsa. very easy to work with and theres prob better products on the market.with all the great new products and technologies do your research. i couldnt see using balsa again
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Old 06-17-2013
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Re: Practice deck core layups?

I would still use balsa. Strongest in compression for its weight. Water will not migrate far because of grain orientation - unless left wet for years like many boats have been. Remember that with any core if water gets in it will eventually delaminate and than you start the process again. If the builders of out boats properly potted the fittings and any owners since new installed items correctly there would be no problems today. Balsa is also easy to work with and follows curves well.

Plywood is the worst core you can use - once wet the moisture travels easily throughout it. And it is heavy.

Use epoxy and you do not need to practice - as posted pretty easy just messy.

Here are some links to help:

WEST SYSTEM | Use Guides

WEST SYSTEM | Projects | Fiberglass Boat Repair and Restoration - Fiberglass deck repair-Part 1, Replacing damaged balsa core

WEST SYSTEM | Projects - Boat Repair

Lackey Sailing LLC | Restoring and Rebuilding Great* Boats This is a restoration site that has excellent descriptions with pics of recoring as well as anything else you can imagine an older boat may need.
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Old 06-18-2013
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Re: Practice deck core layups?

Quote:
Originally Posted by mitiempo View Post
Water will not migrate far because of grain orientation - unless left wet for years like many boats have been.
Quoted because this deserves to be repeated.

Foam may not rot, but once you get water in there, you're going get delamination in short order and it will most likely be much more widespread than with end-grain balsa.

It's actually pretty amazing how long the decks have lasted on boats that most people here are now in the process of fixing.

Last edited by mbetter; 06-18-2013 at 02:30 AM.
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