On Tue, Oct 21, 2014 at 12:57 AM, ru-eno@online.no [harryproa] <harryproa@yahoogroups.com.au> wrote:
Thank you Rob,
a few more comments to your answers - please bear with me
- see message history below.
---In harryproa@yahoogroups.com.au, <harryproa@...> wrote :
The mast does have to rotate, but not relative to the sail. A wing section would improve performance, but at the cost of complexity. There are also issues with wing masts in gales and when maneuvering under motor. For the charter boat, a round mast. For a personal boat, whichever one appeals most.
***
I see your point - keep it simple.
***The mast flexes in strong breeze and the top twists, depowering it. The amount of twist is controlled by the outhaul, which runs from the end of the boom to the base of the mast. The tighter it is, the less the sail twists and the more the mast bends. With such a tall mast, there is always going to be excess twist with this system. So, upwind in a breeze, some of the sail will not be doing much. If we get the dynamics right in light air and off the wind, all the sail is working.
***
I see, and with the broad flat topped sail, I guess the issue may easily be too much twist - spilling wind high up long before the ww hull starts to lift. I guess thats fine for a cruiser or fun boat - although some serious racers may object. Perhaps, if less twist is wanted one could add a downhaul from the outer end of the boom to the mast just above the deck (same effect as a cunningham). That could increase leach tension and reduce twist. Also this, I suspect, would not affect sail depth (or camber) as much as the outhaul probably does. But now I make things more complicated again.
Your thinking is correct. but the outhaul is also the vang. ie, the line goes from the clew of the sail, through the end of the boom, then to the mast at deck level. The same line controls the mast bend, outhaul and twist. Hopefully they will all work together, but if not, a second control may be required.
***
-would it be feasible to have both a racing ww hull (as standard), and a cruising one (Solitarry type), and to just pick the one you need when assembling, before launch?No problem at all. However, the beams and maybe the mast would need to be sized for the extra weight that will be in the cruising hull.
***
Sounds logical. So for a cruising only version, would you rather shorten the beams to compensate for that extra weight?
Shorten the beams.
***
- Would a folding option be possible on the Bucket List? Or would it be too complicated and heavy?No problem. Would definitely add weight and cost, but not a huge amount.
***
You mentioned a "fore and aft" folding option for the Expeditionarry (on you web-page), but I have not seen any drawings of that. Would that allow folding on the water so the boat could be kept in a normal marina? And would that mean three hinges on each beam?
It could be done with single hinges (beams rotating round the mast), but the devil in all folding systems is in the detail. Especially when you have a trampoline. The rudders and outboard also need consideration. None of which is impossible, but neither is it trivial.
I guess that may solve the problem of narrow boat ramps as well, but with increased cost, weight and complexity again.
Exactly.
rob
Rune
***
__._,_.___
Posted by: Rob Denney <harryproa@gmail.com>
| Reply via web post | • | Reply to sender | • | Reply to group | • | Start a new topic | • | Messages in this topic (27) |
.