NSW
214 posts
hi chaps
i have a Chinook extn. and when rigging my old Serverne sail the luff and boom lengths pretty much matched what it says on the bag, give or take 1cm.. But now i've scored a Goya 3d and when i rig it by eye i'm getting about 5cm's different in luff & boom than the spec's printed on the sail, which seems way to much
Q - do different brand Extn's have different Datum's ( i think i remember comparing two in the shop years back and they were) and if so what is the difference?? and whats with the boom length ? ATM im using an old rdm powerex mast that should work ok with the Goya
cheers
tried to google it and got nowhere
NSW
471 posts
If the mast is softer and curves more than the length between the head and tack in a straight line will be smaller, therefore the mast will need to be longer.
If this is the case, the sail will rig flatter with more twist as the length between the head and clew will also be less as the head is being bent more downwards.
That or they have miss printed the correct length, if so forget all of the above info.
WA
23647 posts
I find that with my Chinook RDM extension it starts at 4cm on the first hole, as they measure from the pulleys, but you never get the sail that far down. I add 4cm to each sail's luff measurement and that is what I use (but I have the correct mast for the sails so like Matt says yours may be different)
NSW
214 posts
thanks for that, i think i'm the same Mark, adding 4cms would do it what brand sails are you using ? i found two old Extns in the garage and the NP one is 2.5cms different than the Chinook and the other Extn. is different again. its a bit dumb really..
and Goya probably measure boom length from the back of the mast and my NP boom probably from the front, there's the 4cm .. my mast has the right ICMS and powerex and Goya are somewhat suited, well for now anyway
its probably all a bit anal, but was just wondering if maybe the 5.0m was a miss print not the luff and boom length, i don't want a 4.7m
NSW
214 posts
so mark for example if the luff read 417 you would set 413 on the Chinook Extn.
WA
23647 posts
I am using NP Combats and NP mast.
No, the other way around, if the sail requires 10cm extension (as printed on sail) I set Chinook extn to 14cm and downhaul to where the the black plastic end joins the alloy tube - pretty close to the 4cm hole.
