Two things you need to watch out for:
1. That is the same price as the genuine 5.5 blokart sail.
2. The mast sections need to be upgraded to 3 carbon bases, otherwise the mast bend is way out of kilter and can bend your kart mast base.
Cheers
Warren.
waste of good battens and sail cloth! With that much sail way up top you wouldt have a hope of controling the twist . the sail would only become effective when you took it off and put on a 4.0 m. perhaps the sailmaker needs to take a really good look at how a blokart sails
I AGREE WITH LANDYACHT,FROM EXPERIENCE I HAVE FOUND ONLY THE BOTTOM 2/3 OR SO OF A 4m IS REALLY EFFECTIVE AND THIS SAIL LOOKS PRONE TO THE SAME PROBLEM.THAT IS WHY A 3m CAN OUTSAIL THE 4m IN THE RIGHT WIND AS THE WHOLE SAIL AREA IS POWERED UP!I HAVE SAILED WITH THE NEW LARGER SAIL IN N.Z AND AS PAUL BECKETT EXPLAINED IT REALLY IS ONLY TO ALLOW SAILING IN THE LIGHTEST OF WINDS,NOT TO OUTPERFORM THE 4m IN THE STRONGER WINDS.THE FASTEST SPEEDS IN A BLOKART ARE ACHIEVED IN THE STRONGEST WINDS WITH THE SMALLEST SAIL SUITED TO THE CONDITIONS.stevo
what i am waiting to see is a blokart sail where the boom extends forward of the mast and a small jib is attached that moves with the main.
this swing boom idea was used and still is used in rigless remote control yacht racing, not the IOM class nut the marbleheads used then extensively.
they were simply called a swing rig, and amazing ly easy to get the hang of.
Yeah, that's how the RC yacht I build is set up although the jib boom is completely seperate to the main boom. You can even goose wing them down wind and it only requires one winch servo to trim both sails. It would work but I don't know what it would do to your COE.
Hey, they look great. It would be good to have a few others to race against. Knowing how much time and effort goes into building them, someones going to get a good deal there!
This is a picture of one of the ones a mate and I made from the "One Australia" plans. I built the balsa strip plank hull below and we used that as a plug to make 2 yachts. Unfortunately they don't conform to any class so we could only race each other.
Hi..I think i can answer this one... several years ago i sailed a "freeflight" landyacht which was a copy of the "manta" class landyacht in the US, I bought the yacht from the maker with 2 sails one was a standard 4.5sqm the other was 6.5sqm similar to the pic of the large sail on the blokart at the start of this thread.
I found the sail VERY powerful in light winds and starting but after that it was useless altho it provided a very comfortable ride with all the mast flex.
The standard sail landyachts normally caught up after a short time and then overtook in med+ winds.
The reason that sailboard guys WANT twist is that they pull the sail INTO the wind and this gives them LIFT much like an aeroplane wing giving UPWARD LIFT and reduces the resistance and drag of the board in the water and with little or minimal resistance they go MUCH faster...and we all know "Speed is King".....
The other thing you have to take into consideration is the windspeed across the sail.
If a dinghy sails in 15kmh wind the apparent wind speed across the sail at full speed may reach say 20kmh.
If a sailboard sails in 15kmh wind the apparent wind speed across the sail at full speed may reach approx 40kmh (and thats fast on water)
If a Landyacht sails in 15kmh wind the apparent windspeed across the sail at full speed may reach 80-100kmh ( that is tornado force)
So it actually slows you down in a landyacht if there is to much twist in the sail...
So i hope this answers the question of why water yacht and land yacht sails are quite different in design.
I have just found a pic of a blokart or similar with a large sail.
The pic shows clearly the amount of twist a large sail gets, the top section maybe at least 20-30 deg different from the boom and there for reduces the speed of the yacht.
I found this Lift vs Drag diagram.
This shows that a low apect ratio sail has more lift mainly in the 30-40deg region BUT it has LOTS more drag.
Where as the higher aspect ratio sail has LOTS more lift in the 15 deg region.
Just for the hell of it.....
how many of you out there have a 5.5m sail?
I have one on its way.
i was quite impressed by the blokart 5.5 at gillies they sailed well the really light winds/softer surface. the examples seen on this thread had a "big head" that theblokart original doesnt have.
im told by the blokart sailors that they have a set top speed and that was apparent in that they didnt always win and could be caught when a slight gust came in .
i'm quite impressed that blokart pulled off such a big sail on a small light yacht.
That is an awesome picture Gizmo, it helps to explain a lot.
Can you say from the diagram that a pinhead sail has a higher lift to drag ratio than a windsurfing 'fat head' sail?
If so, why aren't the super fast windsurfers using pinhead sails?
Aerodynamics is such a fickle beast, the moment I think I understand it the concepts slink away into the darkness 
Just as a 'for instance', here's the current world water speed record holder. Note how much twist is in the sail...
Surely if a sailboarder wants lift from his sail and so angles it into the wind, then both a pinhead and fat head sail will provide vertical lift and therefore less wetted area (and friction)?
I just find it really curious that two disciplines (sailboards and landyachts) with similar constraints prefer totally different designs of sail.
Gizmo: That sail doesn't look all that flat to me, it's got many cams and the sail is touching the boom from the clew almost to the harness lines. That normally means mega draft...
G'day Brian,
I felt I should comment on twist here, as I have changed my views on it after racing 5s in US & Standart in Belgium.
That sail twist is actually very effective if done without flutter (problem in the old days) and also becomes part of the "energy storage / return" process of the yacht itself. This works in conjunction with (using a blokart as example) axle flex, mast and chassis flex. It's not as bad aerodynamically as you might think and is a way of making some sail area "disappear" at higher speeds.
Even Vindicators wing works better with a twist at 140 kmh.
