DRAGONFLY Trimarans User Forum

I am interested in a Dragonfly 25.I understand that the deck on the middle hull has a core of balsa or similar.

What about the hull is there anyone who can tell me if the hull is built up by just fiberclass or if the hull has a sandwich design with a core of balsa or similar?


The reason for my question is that I want to start multi hull sailing and I have found a Dragonfly 25.

The problem is that the boat has been in a marina in Sweden and rain and snow has filled the middle hull with 50 cm of water and it has been filled with water for years. I have got an offer to buy the boat and my plan is to rescue the boat and do a renovation. But if the middle hull is built up with sandwich I guess it is a risk that the sandwich is completely soaked with water and the boat cant be repaired.

Gunnar

I don't know about the DF 25, but in my DF 800 (1998) the main hull is sandwich, too; except the bottom, which is massive to protect the hull in case of a grounding. You can see from inside if it is sandwich or massive, as sandwich is thicker.

The lower part of the GRP is painted inside with white topcoat to protect it from water, is it the same with the boat you have seen?

My handbooks says: "DF is built of (...) fibre glass and polyester combined with 10 mm PVC sandwich foam core." The brands are "Divinycell, Airex or Klegecell".

Niko

I have a Canadian built DF 25. The sides of the hull are not cored but the very bottom may be.

It sound reasonable that you could make some small holes to investigate as this boat sound like it is in pretty bad condition and what are a couple of holes going to do? If the core is wet a 2mm hole would drip enough to prove it. Also a moisture meter would be helpful.

I have a Canadian built 25 as well. It appears that the deck is cored as well as the hull, I haven't drilled any holes yet so I'm not 100%, but darn close.

I also suspect Niko is right and that the very bottom of the hull is solid.
This is in fact how the floats are contructed. Sandwich deck, solid "keel" and boot stripe and a sandwich layer in between. PAY ATTENTION TO THE FLOATS. The inner layer of glass on mine was never quite soaked solid with resin, and thus let water in. That in combination with leaking bedding compound and PO's not keeping it bone dry in there made the balsa rot and the whole thing de-laminate. (not sure about the Danish but the CA boats had balsa) Here's what you are in for if that happens to you:

http://www.dragonfly-trimarans.org/phpB ... ?p=877#877

So, get a surveyor who knows what he's doing and who knows how to operate a moisture meter.....