Interesting.
May be good for larger sails.
For smaller sails (sub 7.0 or so) a loop, hook, and pull system (like Cyclops) is way faster and takes no tools.
Not sure how I feel about carbon vs. metal on extensions.
Clever, like a mechanical Noer stick. Interesting to see how the screw jack (I'm assuming that's what's essentially inside) holds up to corrosion, sand and how much mechanical advantage is lost over time to both and the lack of lubrication. Agree with aeroegnr that smaller sails are simple and low tension enough not to need to spend the funds to complicate the process.
The only thing about carrying the driver/tool on the water is the opportunity for it to join about ten thousand pairs of sunglasses at the bottom. 
Using my Duotone ratchet extension is getting a bit habit-forming. I can certainly see the appeal of alternatives to sitting on wet grass and pulling on the downhaul.
Do these tools provide feedback when tensioning?
It's one of the reasons I like doing it by hand so I know if something feels off, head not in right, junction slipped open, wrong extension, etc.
Select to expand quotePaducah said..
Clever, like a mechanical Noer stick. Interesting to see how the screw jack (I'm assuming that's what's essentially inside) holds up to corrosion, sand and how much mechanical advantage is lost over time to both and the lack of lubrication. Agree with aeroegnr that smaller sails are simple and low tension enough not to need to spend the funds to complicate the process.
The only thing about carrying the driver/tool on the water is the opportunity for it to join about ten thousand pairs of sunglasses at the bottom.
Using my Duotone ratchet extension is getting a bit habit-forming. I can certainly see the appeal of alternatives to sitting on wet grass and pulling on the downhaul.
I agree with you on the ratchet extension; I've got the older North Sails version and it's great other than being particular about the kind of rope used. It's super convenient that you can easily adjust downhaul tension out on the water.
Like you, I assume this thing has a pretty fine thread jacking screw inside. That should be VERY easy to seal reasonably well with a carefully placed o-ring or piston-style seal to keep the water/sand/zebra mussels out and lubrication grease in.
However, adjustment out on the water means separating the sail from the board to get access to the screw point. It seems that a right angle drive with a worm gear would be a better choice for two reasons - easier adjustment (from the side, can be done while attached to board) and lower risk of the screw "unwinding" itself and releasing tension over time while in use.
Also, if you've got a high tension sail that only requires a bit of extension, you'll still be pulling on that downhaul rope pretty hard before you get to the crank mechanism, kinda defeating the main benefit here.
Duotone Power XT, do yourself a favour, hands down one of the best pieces of windsurfing hardware ever made.
Select to expand quoteozzimark said..
.... Also, if you've got a high tension sail that only requires a bit of extension, you'll still be pulling on that downhaul rope pretty hard before you get to the crank mechanism, kinda defeating the main benefit here.
I really overlooked this one. Good point.
So this is a double-sleeved mast extension for SDM masts with a mechanical thread inside, like a car jack.
How much does it weigh? (Must be very heavy, compared to a normal extension)
I see you still need a separate winch handle to change tension on the beach.
Why is the downhaul rope still threaded and used - when a hook on system would suffice with this extension?
Presumably there's not one for RDM masts because the mast diameter probably wouldn't allow for a small diameter version of this system to fit.
This is another toy for people who like gadgets - more than they like windsurfing.
Looks like an answer to a question nobody asked. Again. Seems to always be extensions and bases. Is there a uni design course in Europe that suggests "design a better chair or windsurfing base"...?
If you wave/freestyle/crossover its not needed.
If you have high downhaul sails there are winches that cost bugger all and can't stuff up.
I have never ever had the desire to change downhaul on the water nor do I know anyone who has - but if you feel the need there's the XT and this can't be used for on-water adjustments.
So WTF
Select to expand quoteBasher said..
Why is the downhaul rope still threaded and used - when a hook on system would suffice with this extension?
If the mechanism jams up during a session (I think anything in WIndsurfing that slides or turns is fair game), then at least its possible to derig.
Do people really have that much trouble downhauling their sails they need winches etc?
Select to expand quoteBen1973 said..
Do people really have that much trouble downhauling their sails they need winches etc?
If you are not using a tool to downhaul big sails, then you doing yourself a disservice - either because it will do your back in, tools allow fine-tuning of your gear.
Select to expand quoteBen1973 said..
Do people really have that much trouble downhauling their sails they need winches etc?
Yep, at 78 I no longer have the strength or back to downhaul a fully cambered race/speed sail to it's optimum amount. I can probably still get my wave sails right, but I haven't tried that for a while.
I have both SDM & RDM Duotone/North Power XT extensions. I use with both slalom and wave sails. As Choco said "Hands down the best bit of windsurfing kit ever". I wouldn't use anything else. Easy to use in the rigging area and on the water, a feature I use regularly. Also easy to clean & maintain. Duotone fully support with spare parts.
