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Moderated Duo 900 Italy

 

Hello Bernd the Duo 900 the construction has come to an end, I'm waiting for the sailmaker who brings me the mainsail and the jib to assemble it before launching into the sea.
Ciao
link?/g/K-designs-Multihull-Sailboats/album?p=Taken%2C%2C%2C20%2C1%2C200%2C0&jump=1&id=256248
 

Hi Domenico

Thank you for the photos.
Looks very good, as usual.
Do you have any idea how long it took to build the boat?
Any idea will be helpful.
I know it was only stop work in between building the KD 122.

So next week sailing?

Ciao
 

Bernd if I had to build a new Duo 900 I would finish it in 7/8 months finished.
The pandemic broke out during the construction of the Duo900, plus it was a problem to receive the pipes to complete the construction. The pipes were in Milan and as you know I live in Peschci (Puglia south Italy) and I could not receive them...
Then there was a customer who blindly believed in the KD122 with the A-Frame mast and then from there it was a big slowdown for the Duo 900.
Now I'm happy that it's almost finished, that as you know (on your projects under 10mt) I strongly believe the Duo900 will be the silver bullet.
The Duo is not difficult to build, you have to be careful about the connections of the pipes and the various reinforcements to follow, everything is there for the stability of the boat.
For the launch at sea I have to bring it back to Puglia I will let you know soon.
 

7/8 months? So for us normal boatbuilding people, maybe 15 months. Not bad for such cool design. Once again, Dominico, I am super impressed not only by the quality of your work but also your speed. And that Duo900 looks like it will be fast.

I am curious about the mast head. Do you have any other shots with more detail of the mast head? I will be shortening the mast from a Hobie 16 for my ECO 6 and building a new mast head for it. I am thinking of using wood (both plywood and some solid wood) reinforced with carbon fibre. Any advice?
 

Hi Rod
The Duo 900 is not a difficult construction, you have to pay attention to two crucial phases.
First you have to be careful about the positioning of the BHs because when we are going to close on one side with the plating, the rear part tends to lean due to the weight and therefore when we place the plating on one side, we have to put support poles underneath .
According to the locations of the placement of the pipes, you must have the 180mm pipes immediately
? and once the hulls have been turned, position the two tubes with screws without resin and after that it will be easier to finish everything.
?
On the head of the mast is a glued mahogany plywood, resin and fiber cap. Immediately below the two recessed blocks in front and behind. Soon I will put some photos on the wing mast.
If you are interested in the wing mast I have templates to build it even 9mt at no cost ;-)
 

Rod, does your Hobie 16 mast have a comptip or is it a single length of Aluminum? It makes a big difference on how to build a new masthead. If it is Aluminum, you can just reuse the original masthead.

I have made a bunch of mast fittings using polyester resin and fiberglass chopped strand mat. Strength is only 13,000 psi but it can be any shape you want and is pretty much the same strength in all directions (isotropic). To put it into perspective, the fiberglass has to be just over double the thickness of Aluminum to be the same strength. This particular fiberglass material does not have grain like wood, doesn't rot and takes paint well. It can also be re-shaped by woodworking tools after molding.

I make molds from rigid foam and cover them with packing tape. Even semi-enclosed components can be made this way. I just use a small amount of acetone to melt the foam after the fiberglass is cured and then pick out the left over packing tape from the inside of the part with long-nose pliers.

Wood and plaster of paris can be used to make less complicated molds that are not enclosed. Again, covering the mold with packing tape will work as mold release.

David M

On Monday, April 24, 2023 at 09:08:59 AM PDT, Rod McLaren <nkosuohene@...> wrote:


7/8 months? So for us normal boatbuilding people, maybe 15 months. Not bad for such cool design. Once again, Dominico, I am super impressed not only by the quality of your work but also your speed. And that Duo900 looks like it will be fast.

I am curious about the mast head. Do you have any other shots with more detail of the mast head? I will be shortening the mast from a Hobie 16 for my ECO 6 and building a new mast head for it. I am thinking of using wood (both plywood and some solid wood) reinforced with carbon fibre. Any advice?

 

Thank you for that suggestion, David. More options to consider... just when I thought I was getting to the end. :-) The Hobie mast is a solid aluminum one - fortunately not one with the comp-tip. The mast head is a large single sheave which does not allow attaching a mast head light or wind indicator or such and that is why I want to change it. I will keep your idea in mind when I get to the mast. Just now, I am still looking for that "good enough" point on sanding the topsides after fibreglassing it all. -)

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