Crosslinked PVC vs Balsa Core for Foils

[CatBuilder]

Would you use crosslinked PVC foam or Balsa for core material on foils?

Why or why not?

[marshmat]

I'd probably prefer high density Core-Cell.... I suppose a lot of things would work, though, the specifics to depend on the actual application. On a cruising boat, for example, tough and impact-resistant will likely take priority over light weight- while a racer might want lighter, though less durable, cores.

[CatBuilder]

Originally Posted by marshmat

I'd probably prefer high density Core-Cell.... I suppose a lot of things would work, though, the specifics to depend on the actual application. On a cruising boat, for example, tough and impact-resistant will likely take priority over light weight- while a racer might want lighter, though less durable, cores.

Very good points, thank you.

A material choice without a specific application in mind is almost meaningless. I can see where I should have included that.

The application is for kick-up rudders and for dagger boards with crash blocks on my catamaran build. The boat is a world cruiser and will be used away from docks for extended periods of time.

A perfect core material for such application would be KIRI wood (Paulownia tomentosa) But it is hard to get.
It is nearly as light as Balsa but several times stronger, and the shear strength is far better than in any other common core material.

It does hardly rot (one can bury it for 50 years without rot).

Regards
Richard

I did not know of it's qualities - and sometimes pretty, too. Sounds like a perfect plantation tree. Thanks, Richard.

[Herman]

I doubt between high density Core-Cell and Balsa.

The pro of balsa:

-cheap
-high compressive strength, which helps at points like the end of the daggerboardcase

The pro of Core-Cell:

-high impact strength
-easier to work with.

If possible, use the S version of the foam.

[CatBuilder]

Ok, same question, but for the deck and deckhouse.

Would you use corecell or balsa AL600 for a deck and deckhouse? I ask because I have an option to buy corecell at a good price for the entire deck/deckhouse. My hulls do not have coring - they are ply/epoxy.

Originally Posted by CatBuilder

Ok, same question, but for the deck and deckhouse.

You may have overlooked post# 4?

[kyle@raka.com]

Originally Posted by apex1

A perfect core material for such application would be KIRI wood (Paulownia tomentosa) But it is hard to get.
It is nearly as light as Balsa but several times stronger, and the shear strength is far better than in any other common core material.

It does hardly rot (one can bury it for 50 years without rot).

Regards
Richard

Interesting point richard, we actually have found a good paulownia retailer and are trying it out for a paulownia version of a cedar strip canoe. Good stuff and amazingly light. lol we had a 2 x 6 x 8ft and it was pick up with less than 1 hand amazing.

[Herman]

If it is not available in the area that the topic starter is in, then it is useless.

For a deck I would not use balsa. As I have said so many times before, balsa and unprotected holes through the sandwich is a bad idea. If you are building for durability, there will be a time that either some holes will start leaking, no matter how much care you have taken in sealing them, and second, a boat deck is one of the rare occasions where end users, or next owners, will drill holes in and do adaptions so many times. And many of these people do not have the knowledge to properly protect the balsa from moisture.

In terms of durability: There is no great need for a high impact strength on decks, so with balsa you are OK. But do protect your drill holes, and put a note in the logbook, with instructions on how a well protected hole should look like. (and I know that holes in a foam sandwich should be protected as well, but the damage done is so much less if things go wrong).

I still see an optimum in price/performance of a Core-Cell hull, and a PVC foam deck, or if weight is a little bit less important, and the building method allows it, a balsa hull and PVC deck.

[Stumble]

Herman,

I have seen damage in foam cores spread just as fast and do just as much damage as in balsa cores. The problem isn't wood rot of course, but hydrostatic preassure that will pulvarize the foam.

The problem in my eyes is with owners that do not understand their boats, and salesmen that shade the truth or lie about the characteristics of the boats they sell.

Originally Posted by kyle@raka.com

Interesting point richard, we actually have found a good paulownia retailer and are trying it out for a paulownia version of a cedar strip canoe. Good stuff and amazingly light. lol we had a 2 x 6 x 8ft and it was pick up with less than 1 hand amazing.

As mentioned Kiri is as light as a high density Balsa, but several times stronger in every aspect. A perfect core (in fact the only stuff I accept as core material), and a perfect deck when proper supported (sheathed or ply covered).

Let catbuilder have your source!

and:.............it was pick up with less than 1 hand amazing............
which organ did you use to pick it up?

Herman

Originally Posted by Herman

If it is not available in the area that the topic starter is in, then it is useless.

exactly that was stated above by Kyle! It IS available.

Regards
Richard

[kyle@raka.com]

lol richard got it with my left hand and im right handed

Anyone drilling holes thru a deck without taking appropriate measures shud go back to stocking shelves or whatever they did before.


I built this deck in 1984. It is 12' across and spans 10' fore and aft without framing. I have had a four hundred pound halibut going berzerk, 21,000 lbs of cargo on deck, spilled bar-b-que, gaff hooks, a rock slide, a 1lb. shackle thrown off of a ship (that one needed repair), and there is no cracking, no moisture in core.
Yes, the kiri sounds amazing and I trust Richard. I will look into this wood.

[kyle@raka.com]

We have tested some of the paulonia wood we got a few people we can buy from but the best site we have found about it is www.PaulowniaLumberAndSupply.com
If you give us a call we can see what we can find your projects and what prices (obviously a buisness buying in bulk can get a better then list price)

Kyle
www.Raka.com