Klaus Riedl of Hamburg Germany built this Tamanu and powered it with a 10 sq meter (107 sq ft) windsurf sail. Windsurf technology has been at the leading edge of sailing for a long time and it would be hard to imagine a more efficient sail. Yes, I know a kite might be faster yet... unless you happen to need to go upwind.
I was fortunate to be an addicted windsurfer during the transition period between soft sails and what is now essentially a rigid wing. The difference in handling in strong gusty conditions is astonishing and you can handle much more area than you would expect. I doubt that he'll need to reduce sail very often.
I think it may be the flogging of the soft sail when it's over powered that causes a lot of drag. The modern windsurf sail (with maybe 200 lbs of downhaul tension)stays stable and well behaved even when eased.
Kites can sail about 70 degrees from the wind direction whereas a windsurfer can do 45 degrees. So a kite can do what a square rigger could do 200 years ago.
While the semi-rigid wing can no doubt outperform a traditional soft sail, a great deal of the performance of windsurfers with this type of sail has to do with the thrust vectors involved when the whole thing is tilted to windward and develops upward lift...
that also plays into handling and the need to reef, as the higher the winds get the more you can tilt the rig and turn energy that would normally be trying to tip everything to leeward into a force that effectively un-weights the hull.
Obviously not "easy" if you are doing it manually on a surfboard, but a similar semi-rigid wing with the ability to tilt into th ewind could create a rig that *would* have a far greater set of power development parameters than just on/off or full/luffing and could be easier to handle because of it assuming the tilt was more or less a hands-off affair.
Absolutely Awesome! One single sail that can outperform most. Thats the way I am going with my Ulua project. (Dreamabout)Congrats and thank you for the inspiration. Tks Bira DeAraujo
Pretty cool. Hey Gary, can you recommend a windsurf rig (sail size, mast stiffness, etc) for the Ulua? There is such a wide range available. Since we are moving a much heaver boat vs a board does it make sense to go with a large (for a board) sail like a 11 or 12m2 with a very stiff mast??
I've been toying with the idea of using a 7m windsurfing rig (an old gaastra GTX) on a shunting 16ft wa'apa, my brain is telling me that you could then sail with the rig in its designed orientation, raked rearward and to windward making use of the lift then. You also gain by being able to put a touch more downhaul if its windy to get the leach to loosen off, rather than changing rigs. Anyone fancy chiming in on if this would work in practice?
A very convincing sail until you need to reef it. I am assuming you cannot reef this, only drop it (and so the stub mast is a good idea here).
ReplyDeleteI was fortunate to be an addicted windsurfer during the transition period between soft sails and what is now essentially a rigid wing. The difference in handling in strong gusty conditions is astonishing and you can handle much more area than you would expect. I doubt that he'll need to reduce sail very often.
ReplyDeleteInteresting. Is it the battens that provide this quality? The sail will not flog, so you can depower with the sheet?
ReplyDeleteI think it may be the flogging of the soft sail when it's over powered that causes a lot of drag. The modern windsurf sail (with maybe 200 lbs of downhaul tension)stays stable and well behaved even when eased.
ReplyDeletehi Gary, kites can sail upwind these days, check out climatevoyagage.net for a choice papuan 48 foot canoe btw.
ReplyDeleteKites can sail about 70 degrees from the wind direction whereas a windsurfer can do 45 degrees. So a kite can do what a square rigger could do 200 years ago.
ReplyDeleteSorry climate challenger is papuan canoe :)
ReplyDeleteWhile the semi-rigid wing can no doubt outperform a traditional soft sail, a great deal of the performance of windsurfers with this type of sail has to do with the thrust vectors involved when the whole thing is tilted to windward and develops upward lift...
ReplyDeletethat also plays into handling and the need to reef, as the higher the winds get the more you can tilt the rig and turn energy that would normally be trying to tip everything to leeward into a force that effectively un-weights the hull.
Obviously not "easy" if you are doing it manually on a surfboard, but a similar semi-rigid wing with the ability to tilt into th ewind could create a rig that *would* have a far greater set of power development parameters than just on/off or full/luffing and could be easier to handle because of it assuming the tilt was more or less a hands-off affair.
Absolutely Awesome! One single sail that can outperform most. Thats the way I am going with my Ulua project. (Dreamabout)Congrats and thank you for the inspiration.
ReplyDeleteTks Bira DeAraujo
Pretty cool. Hey Gary, can you recommend a windsurf rig (sail size, mast stiffness, etc) for the Ulua? There is such a wide range available. Since we are moving a much heaver boat vs a board does it make sense to go with a large (for a board) sail like a 11 or 12m2 with a very stiff mast??
ReplyDeleteThanks,
Jim Ketterer
Thanks for your friendly comments...
ReplyDeleteThe main advantage of surf riggs is:
Very low weight
Many riggs available (also used)
Low costs
So I have 2 riggs:
8 qm2 for sailing alone or heavier winds - and a 10 m2 rigg for easy winds or 2-3 persons.
Best regards Klaus /Hamburg
I've been toying with the idea of using a 7m windsurfing rig (an old gaastra GTX) on a shunting 16ft wa'apa, my brain is telling me that you could then sail with the rig in its designed orientation, raked rearward and to windward making use of the lift then.
ReplyDeleteYou also gain by being able to put a touch more downhaul if its windy to get the leach to loosen off, rather than changing rigs.
Anyone fancy chiming in on if this would work in practice?
looks great!
ReplyDelete