Insulation (balso or other)

[geronimo]

Most boats have the hull insulated with balsa. Some have Divinycel (Hallberg Rassy, Bavaria), some have no insulation other then on deck (Bowman, Oyster), some have their own insulating material (Island Packet). Any thoughts on the quality of different insulations?

 

[PBooth]

Hi, I think that you maybe mean 'sandwich construction', the balsa or foam is there to produce a stronger laminate while keeping the weight down compared to solid GRP. A small amount of thermal and acoustic insulation will be a result, but the aim is strength with less weight.

Peter

 

[boatmike]

Correct. The "sandwich" is like a beam. Imagine the two GRP skins as the top and bottom of an "I" beam with the foam or balsa in between as the upright keeping them apart. There are different densities of material for different purposes. There is no "best" material for all use.
If weight is not a problem end grain balsa is usually chosen, as it is more stable, easier to bond to and very strong, there is little to choose between the different manufacturers of PU Foam but it is used where weight is a consideration. Therefore a cruiser will usually have GRP / Balsa sandwich for say a load bearing deck (but may use foam in the hull) where a racing boat could have Kevlar or Carbon skins with lightweight PU foam in the core. No two boats are the same and it is usually a choice based on weight, cost, and function.

 

[geronimo]

Re: Insulation (balsa or other)

Thanks, but if it was mainly structural would it not be used at the bottom of the hull as well (it is never used there). It seems to me that above water it is mainly for insulation, while on deck it is mainly for weight and insulation. And it works very well.

Most boats use balsa but there are some articles about balsa turning into a spreading compost if water finds its way into the "sandwich". And it seems to be almost impossible to repair. Is that a very rare problem or not, I guess is my question.