Cored Hull - power boats

[bheston]

Looking at options for power boats and I found a nice 2004 Chaparral. However, I notice the ad said "balsa cored hull." I didn't realize these had cored hulls. Is the ad wrong? Is this common for smaller (25-30') power boats to have cored hulls? Are there brands that don't or is this typical?

[ranger58sb]

Manufacturers are often making some trade-off decisions. Cored hulls are usually lighter, so you can maybe get higher speeds, or burn less fuel, etc. Nothing particularly wrong with cored hulls, as long as all penetrations are done properly.

I don't know anything about the Chaparrals. A bud had an older one one back in the '90s, seemed OK.

-Chris

[bheston]

Would it be fair to say "most" power boats have cored hulls?

[FPNC]

I spent decades in the fiberglass boat building industry. Built hundreds of cored hull boats. By that I mean literally with my fingers in the resin. A cored hull would be my last choice. A balsa cored hull would be off the list. It's not worth the risk.

[rslifkin]

Originally Posted by bheston

Would it be fair to say "most" power boats have cored hulls?

I would say no. Cored hulls are more common on higher performance or lower cost powerboats. But I'd say that in the realm of slower powerboats and earlier fiberglass builds, cored hulls are fairly uncommon.

[billknny]

There is a great story in one of David Gerr’s books about a salesman coming to his office with a cored fiberglass sample. After bragging on the great strength and light weight, the confident salesman handed David a hammer, “Go ahead, hit it as hard as you can!”

David, being a think out of the box kind of guy, rotated the hammer 90 degrees, and hit the panel with the claw end, punching a hole clean through on the first strike.

Balsa cores are light, strong, and stiff, but NOT tough. Not that no boat should built that way, but certainly not every boat.

[FPNC]

Originally Posted by billknny

There is a great story in one of David Gerr’s books .

Balsa excels at creating stiff panels with thin skins and for a relatively nominal price.

Due to the extremely high compression strength of end grain balsa, it can be very stiff with thin skins. Unfortunately, this means that when the external skin is impacted hard in a small area (think hit with a bowling ball) that force is transmitted directly to the inner skin. With the lack of compression absorption that is found in a softer foam core, the external impact on a balsa cored laminate can cause great damage to the internal skin. Usually a shearing type delamination at the cores bond line and/or delamination in the laminate layer next to the core.

[lvictorlucas]

Stay away from Balsa because the slightest crack will result in saturating the core. Song cars are good making a much quieter and lighter hole. Definitely check the outer layer thickness though. What I like is how much quieter it is and you get a lot of insulation thrown on top.

[SofiaB]

Originally Posted by FPNC

I spent decades in the fiberglass boat building industry. Built hundreds of cored hull boats. By that I mean literally with my fingers in the resin. A cored hull would be my last choice. A balsa cored hull would be off the list. It's not worth the risk.

Smart man. It took a lot of research to find a boat with no core material below the waterline and no wood coring above the waterline. There are boats out there but getting harder and harder to find.

[SteveSadler]

Balsa is the best core material and saves half the weight of a hull and deck. A huge advantage. Yes it doesn't like point loading but half the weight also means half the horsepower and fuel are needed.

[rslifkin]

Cores definitely have their place, but I don't like hulls that are cored below the waterline. Too many potential issues relative to the benefits.

On the other hand, cored structures like my bow pulpit are a good idea. It needs to be thick, strong and stiff, but building it entirely out of fiberglass would be incredibly heavy. As-is, it's got 1/2 and 3/8 inch thick skins with an inch of core in between. Impact resistance wouldn't really be any better if it were solid fiberglass, it would just be heavier.

[bheston]

So how can you tell? If you are looking at a used boat in the 2000 to 2008 era, how do you know if it has a cored hull below the waterline? Obviously you cannot ask the broker if you can remove parts and take a peek.

Has someone created a list or brand/manufacturer guidance?