G'day, You are right (and I am wrong) about 2 masts vs one. The stiffness and the strength are different, and it is the strength which needs to be enough to...
Hello ,I was watching the video of the visionary sail, sweet looking boat. But I have a few questions? The mast looks very whippy or flexing alot with the sail...
G'day, Not as whippy as it looks, but could be stiffer, I agree. The sail also needs a bit of work. With a bit more cunningham, the sail would have pre bent...
Rob, You are talking about boats like the harrigami that you anchored a few times? Bucket I understand. Elemntarry is so small I see it tight up against the...
Robert, I'd like to sense a failure ahead of the crack, split whatever, so as to salvage the mast and simply add more glass around the outside. But that would...
Yes, Harrigami and Harry. Anchored out with the lead mines. It is worst in tidal areas or with swirling winds because the boats move around quicker. If...
If it is composite, you will hear a lot of creaking and cracking before it breaks. I would work on one of them doing the lifting as in a capsize you will...
Rob, ...... or anyone else on the forum... Ever figure out what is hull speed for an asymmetric proa design ? Or how the current mathematical approximations...
-I was giving a lecture the other day about diffusion rates of CO2 across stomata of tree leaves- big topic at the moment with CO2 increases effectively...
Rob, Is composite glass/kiri? Doug Rob Denney <proa@...> wrote: If it is composite, you will hear a lot of creaking and cracking before it breaks. I...
G'day, Yes, but the stiffer it is, the more cracking there will be. My understanding of this is that the noise is the resin cracking as the carbon is so much...
Hi Rob, I dont see why the resin should crack because the carbon is stiffer. If the resin cracks it is because it is stressed beyond its maximum strength. The...
G'day, Makes sense, I think. I am pretty sure that a carbon laminate cracks sooner than a wood epoxy one, but have absolutely no data to back this up. Must...
Peter, The point about matching strains is a good one, but I believe the carbon's modulus is magnitudes higher than that of the epoxy matrix, so we won't...
I think I have solved the rudder problem. Why not build a third hull! Seriously just a small thing that runs between the beams where the current rudder...
If the modulus of the resin and fiber were the same we wouldn't need to add the fiber in the first place. There is an order of magnatude difference for epoxy...
Hi Mike, Fair enough, I am in a similar position, as a machanical engineer, but with some background in composites which is unfortunately largely forgotten. ...
G'day, Good thinking. There is a 60 footer on the drawing board which uses something similar, but midway between the hulls. Owner paid us to build a 15'...
Rob, I googled multihull mailing list and got confused. Can you give me that link. I have run across it but never joined. Thanks. I am inchanted with the...
It would be nice to know the cause, as it may have implications for fatigue or simply to put my mind at rest when I hear the boat creaking and cracking in a...
... and this is may be a better way than hanging them off the beams. Do you want to try it on your boat? ... I can see the rudders in the LW hull, or on them...
After much research, I agree with both Peter and Rob. In summary: epoxy cracking likely occurs in first tension on the leading edge, while structural failure...
-Thanks Mike, I didn't realise that carbon had greater stetch before breaking than glass. My thought on the creaking and cracking concur with yours that it is ...
G'day, Excellent. Any ideas what you want it to look like, or dimensions? Let me know, I (or you if you like) will sketch it, we can discuss it and proceed...
