Hi there
I have an old windsurfer from the early 90's. It has a one-piece carbon mast and came with five Gaastra sails. I'm unable to use all but the two smallest sails because the mast is not long enough, even with the extension that came with the windsurfer.

So here is where my confusion comes in. First, how are the extensions measured? The overall length of my "Shredder" extension is 12" (30 cm). But the difference between the lowest setting and the highest setting is only 3" (7.5 cm). So is this a 3" extension or a 12" extension?

Second, how far does the mast have to slide onto the extension? I'm assuming that one doesn't always use an extension, just a base, and from the pictures of bases I've seen on the net the mast would then only slide on about 3 or 4". If that is the case then I'm thinking I could drill a couple more sets of holes so this extension would lengthen the mast a couple more inches.

Third, I assumed that the extensions would be a 'standard' diameter. But I ordered an old 'Fleetwood' aluminum extension off ebay and it turns out to have an outside diameter of 1 3/4". My original extension is 1 7/8". Seeing some of the extensions on the net I'm guessing that there was supposed to be a plastic (nylon?) cap which would make it the right diameter. Is this likely?

The base that came with the Fleetwood extension isn't the right match for mine. And my base won't fit in the Fleetwood extension. The inside diameter is 1 9/16" whereas the inside diameter of the Shredder extension is 1 5/8".

Anyway, the easiest way I can see out of this dilemma is to drill some extra holes in the Shredder extension. There is 6 1/2" from the highest pair of holes to the top of the extension. Can I safely add a couple of inches mast height to this extension?

Thanks
Ross

Someone else who knows the exact equipment can probably answer your question more knowledgably than I but, I think mast bases are measured by the amount of extension they add. For the Chinooks bases, Tall adds up to 48cm of extension, Medium adds up to 28cm of extension, Short adds up to 11.5cm of extension. A stubby adds "0".

I just measured a couple of my Chinook bases and the distance from the top hole to the top of the extension is 5.5 in or 14 cm.

BTW, most of us would be very impressed to see someone rig 5 different sails on a single mast! Unless they are all roughly the same size. I can get a 7.5 m and a 6.0 m on a 460 cm mast but gotta go to a 430 cm mast for my 5.0 m. Also, I don't know if it is the case with your 90's vintage Gastras but different sails require different mast flex to perform best.

What is the range of sail sizes you are rigging on this mast?

what MB said...

-typically mast must have ~6" inside for the extension
-yes, I have drilled holes into extensions to add a couple ", if you don't care that the mast might break or they are old (by the sounds of it) sails, they don't need as much downhaul so likely it's ok.
-Yes, extension are measured by how much they "extend", ha
-there were different diameters but perhaps a sleeve was lost off of yours, I have a couple here for you to try if you are in Victoria (if indeed in Yukon, URSOL)
-Add sufficient diameter by adding several wraps (at top and bottom of the part that goes into the mast) of electrical tape to make up the difference and so it doesn't bind, top it with tuck tape, it slides easier and doesn't get sticky with sun/heat.
-If you don't have a base matching, there were soooo many versions in the 80's, give up NOW and just spend the $100 for a Chinook base, u-joint and mid extension, Windance might have a used one.

BTW- I find one piece masts a drag purely because of storage/transport, get another one, older ones are cheap. 430-460 rigs most sails, I tend to use almost exclusively 430 masts/midsize extension so that's where I'd spend my bucks.

If your new mast is too long (doesn't sound like it's the case here but when you get a 460 it might) you have floating turbans on the sails, you might be able to adjust the sail downward to fit the mast, if they aren't, tie a rope and a floating turban on after cutting a hole into the mast sleeve top, I have a couple of floaters here if you want them.

Thanks for the help guys. Turns out four of the masts are ‘Windsurfing Hawaii’, and the largest one, 6.4 is a Gaastra, Slalomfoil. The others are 4.2, 4.8, 5.4, and 6.0, and the model is Slalom Comp. They’ve all been stored on the top shelf of my garage for the last two years and this is the first summer I’ve had a lawn in the backyard that I could lay the sails out on.

I rigged the smallest sail using the short extension in the second set of holes from the bottom (5 cm/hole). That worked just fine.

I drilled one extra pair of holes in the shorter extension, which left me just under 6” of insertion. But it didn’t help anyway. The only sail I can use with this mast and the shorter extension is the 4.2.

With the mast inserted in the 4.8 sail, and laying the 28 cm Fleetwood extension alongside, it looks like I’d have enough mast length to rig that one. I inserted the mast in the sleeve of the 5.4 sail and the bottom of the sail, with no tension, comes to the bottom of the mast. So even the Fleetwood extension wouldn’t allow me to use the 5.4. And besides, the mast specs a max 30 cm extension.

I’m thinking it might be quite a simple job if I got a piece of aluminum tubing the same diameter, thickness, and taper at the bottom and then drilled it myself and attached the extension pulleys. Not rocket science if I could find the tube. Then I would still be able to use my base. Obviously, I’m trying to do this on the cheap.

Were the masts a lot longer a decade or so ago? Or is it the type of sails I’ve got. They must be a lot taller and narrower than the ones you have, MB. The mast I have is 460 cm. The difference in length between the 4.2 sail and the 6.0 sail is 55 cm.

I am indeed in Yukon, KUS. Although Sidney is my old stompin grounds (Grad ’74), and I am down there a couple of times a year. But I wouldn’t bring my old beat up windsurfer down there…I’d be too embarrassed.

My sails all have adjustable caps (about the size of a shot glass). I adjusted them as short as possible but the mast is still not long enough.

From what I can figure from my calculations I need a 490 cm (or maybe even 520 cm ?) mast with a 30 cm extension.

Thanks again for the advice. Still not sure what tack I’m going to take. ](*,)

Ross

oops, yes, the sails were much taller....WAAAYYY back then......like early/mid 80's ? (others would know better but I did have one of them & it was useless to put things mildly, same problems as you are having, I got sucked in as a newby in the late 80's, paid a guy who knew better $100 for junk, why do people do these things for a couple of bucks.... ). Compare the specs of similar sized sails in terms of luff (height) and boomlength to confirm. I am afraid they won't do you much good learning on these beyond drifting around a bit, you might be best to get different sails later not a different mast if you have a 460 (sure it hasn't been cut, eh?), even sails that are ancient at $10-$40 a pop will be better than these and you will learn much faster. I listed a freebee 4.7 that would be way better than what you have there by the sounds of it, come and grab it next time down....You should be able to at least rig all of them on this mast if they have floating turbans(if not have them perform a bit poorly). A 460 is typically used for 5.0-5.5 and bigger sails to up to max 7.5-8m. which is great for beginner/lo wind conditions.
The 55cm difference in length is not the issue, it's the original much taller sail design thought to be the cat's ass back then.....I bet they all take a really short boom, right? Highly unstable sails, very high aspect and center of effort, not much fun but I guess they worked for some. Wouldn't wanna learn on this old stuff tho, catapult city. Call me when in town or post and I'll pass along that 4.7.

Hey Yukon.

There are couple of things you could do for extending your mast.

Basically all mast extentions are made from T6-6061 aircraft grade aluminium tubing with .0058 wall thickness. The tubing is made so that each size telescopes into the next smaller and larger diameters.
Just check your yellow pages for metal suppliers or workshops where the tubing is sold by the foot. Telescope your extenion up or down or even make up a new extention with your existing tubing and parts. Safe overlap of the tubing is 2 1/2 times the diameter.

or
Using the same T6-6061 tubing in a smaller diameter 1 1/4 or 1 1/8,(most boom tubing) you can make up a short tip extention for the top of the mast that would fit externally over the tip. Use a peice of 1" or 1 1/8" plastic rod like delron or nylon inserted as a stop for your mast. A stainless screw or bolt will holt the plastic rod. Years ago I used a cleat mounted on my tip extention and uphauled my smaller sails.

Hi KUS
I PM'd you (maybe 3 times ; not sure how this thing works) but not sure if the message went thru or not. So here it is in the forum.

Thanks for the offer of that old 4.7 sail. I don't anticipate coming down there until some time in the fall, but I have a brother living in Sidney who could pick it up and send it to me. Do you have any other sails to sell still? Or do you know of a couple of other well-used sails for sale? The freight for two or three sails wouldn't cost me much more than for one.

And thanks for the great tech advice on building an extension, Tom S. I think getting different sails is gonna solve my immediate problem. But I might end up building over the winter too, even if only to check the difference in performance of the two types of sails.

Thanks
Ross

hmmm, yeah, just got all 3...away for a day.

Get your bro to call me 592-3392 and get the 4.7. I have a mid 90's 4.5 UP, the rest would be more $$, so given you want the 4.7, nothing else to donate with it. I know others sell their old stuff at Nitinat in the July/Aug months so trip down might serve to pick up all the gear in the world AND get some decent sailing wind. Good excuse to get away, eh?

Thanks. I'll get him to call you, KUS.

You had advertised about a month ago:

6.0 Neil Pryde VX Racesail, super low end power, serious speed, nice & solid, one new panel $99

I'll buy that from you if you still have it. I hope to have a decent windsurfer sometime, so I don't mind buying some better gear here and there.

no probs, forgot about that one....doubt it would rig on your current mast maybe, it needs a decent 460 carbon. It's older but a wicked unit and you are welcome to it. The thing is good from 5-7+m cuz you can really bag it out and flatten it, huge!! range for me anyway. I held onto that thing all folded over itself when others were on 4.5's

I don't know if the one-piece mast I have is 'decent' or not, but it is a 460 carbon.
I'll give it a shot.
Thanks

UPDATE!!: I just measured my '460' mast and you were right; someone has shortened it at some point to 444.5 cm. No wonder the sails weren't fitting. I guess it may have been damaged at the base in the past?

Won't need those sails now, KUS. Thanks anyway. Gonna have to rethink this whole thing.

yup, tends to happen. In that case just get yourself a 460 by the sounds of it you can then rig it all with your old extension and floating turbans and perhaps the sails are not that anicent afterall. All good!