Balsa core in deck?

[mikelinmon]

Hi Frank C and all,

The first thing mentioned in original note is about owner's noting balsa in the deck! Therefore there must have been balsa in the deck. I noted that owner was referring to a balsa cored boat, hence knowledge of the age of the boat. Without owner mentioning age! My statement stands. If your boat has some balsa in the deck, then balsa is in many areas.

Now as to the beams in the deck. I myself made the first beam panel and the factory worker made a matching balsa cored panel in about 97/98. The two panels were load tested. Roger OK'd use of beam construction in one spot on one boat. That tested stronger than balsa ( we jumped up and down on it). A boat was made with beam core in the deck only and sailed about for a while. We used this boat for a while, no cracks. Then decks were made using only beam construction, each deck weighed by me. The decks were lighter and stronger. Overall weight of the X dropped a lot! They sailed better, stiffer and more upright.
Mike Inmon

[piratetom]

OK, so is a balsa cored boat something to be avoided? One of the boats I'm looking at is a 97X, which, according to this topic, is balsa cored. Mac's website says this is prone to rot, so is there anything specific I need to check for, and if so, how?

[Frank C]

. . . Without owner mentioning age! My statement stands. If your boat has some balsa in the deck, then balsa is in many areas.

. . . The (foam-beamed) decks were lighter and stronger. Overall weight of the X dropped a lot! They sailed better, stiffer and more upright.
Mike Inmon

Point is well-taken . . . thanks.

So, how much did the deck weight change from early '98 to '99?
And does that alone (deck-wt) cause the '99 X to "... sailed better, stiffer and more upright." ??

[Catigale]

OK, so is a balsa cored boat something to be avoided? One of the boats I'm looking at is a 97X, which, according to this topic, is balsa cored. Mac's website says this is prone to rot, so is there anything specific I need to check for, and if so, how?

This is probably where a qualified marine surveyor should step in and give you a professional assessment which you pay for, and s/he stands behind imho.

[mikelinmon]

Hi,

The overall weight reduction of the X during its production was 250lbs. Most of that was hat beam construction vs balsa, but some was lighter liners ( fiberglass cloth vs fiberglass mat ). The M weight has not changed since intro but the new alum trailer is only 600lbs vs 900 for the old steel one. During the same time frame the OB motors went from 165 lbs for the carb 50hp Tohatsu up to over 250 for the Merc Big foot 50hp.
Funny thing about the old 50 hp 2-stroke smokers, I have not yet taken one apart even though we sold hundreds!
Mike Inmon

[ALX357]

Just a clarification. The foam you see in the cabin top cross sections is not "foam core" construction. The resin-saturated fiberglass roving is formed into beams or ribs, or joists, that reinforce the deck and bond it to the liner. That foam is only left in the boat because it is not necessary to remove, after having done its job of forming and supporting the roving ribs until their layup has cured. There is no "foam core".