Bynorthsea asked for some more detail on our windsurfer mast extension mods so here goes.
My mast extension/reinforcing stiffiner is made from a piece of 48x4mm scaffold tube 1000mm long in this version I have salvaged the foot from a real mast extension (but im planning on changing this)
From left to right:
1, Adjustable collar, adjust up or down as you would a normal mast extension note retaining pin bellow collar (detail later)
2, Pivot and mount for boom (see pic 6)
3, Foot from old mast extension
View from other side
Slots in top compress to internal taper of mast
Boom fitted to pivot, boom just slips on, no retaining mechanisim
My next version will replace the old extension foot with this (same as Chook uses)
Using this will allow for change to downhaul tension while underway. (not possible with current system).
Detail of adjustment collar retaining pin.
The pins are 4mm long same as the wall thickness of the ally tube.
The pins support a collar of ally flat bar held in place with a hose clamp.
Excellent thanks very much, it's great to get advice and info from all round the world, not a lot of home building goes on over here.
Forgive me for not knowing the background of this - I assume this just slides onto a fixed pin on the yacht? What dimensions?
Gofaster
See the second half of this thread...
After the part where I tried and failed to support the mast with guy ropes.
Start from my post on "16 Jul 2016 page 1"
www.seabreeze.com.au/forums/Land-Yacht-Sailing/Sail-making/Cam-batten-windsurfer-sails
Here we are with the construction so far, tomorrow I take the angle grinder to a perfectly good mast step.
Interesting adjustable mast step A lot of stress on mast steps Any movement there and it will be noisy and get noisier. Those bolts will need to be done up tight ! Good idea for finding out what's best for tuning your yacht
I wanted to keep the length of the side plates as short as possible, the pin is also set at 5 deg rake to even out the movement. Here is the next stages.
Nice job.
I believe yours is the 3rd instance of this system so very interested to hear your reports and experience.
Select to expand quote
Looking really good there. 
I would put 4 triangular gussets from the boss/base of the stalk, out to each of the top corners of the of the 2 vertical side pivot plates. Also a bit more steel to reinforce and stop the adjustment bolts buckling the base of the mast pivot, as there will be a huge load on the rear bolt.
I'd also make a dimple for the bolts to sit in to help stop them sliding out under pressure
First session today testing the new rig. Typically when we arrive there was very little wind so I put up my 6.2 sail, by the time I was ready to sail it was blowing and very gusty and sailing meant going where the yacht wanted to go rather than being in control, that and a main sheet that did not work well made for very hairy sailing. Changed to the 4.2 in the picture, some more rake, re-route the main sheet and take out the double blocks and I had a yacht that I could sail, have to say that I was amazed at the surge of power I was getting from a 4.2 sail and how it turned cleanly through tacks and gybes. Anyway test went well can't wait to get it with small wheels and on concrete just hope the nerve holds.
I mentioned before that I was planning to make some more modifications to the mast extension.
This version uses a cam cleat and tripple block so that downhaul tension can be changed while underway, as pioneered by Chook & Greg.
Swapped the standard hose clamp for a heavier one
Interesting to hear how easy it is to adjust the downhaul on the move, even with six to one it takes a some hauling to fully tension the sail though if I was going to do it I would run it though a secondary power system to get the relatively small amount of adjustment needed. At my early stage I am going to try and learn about statically setting up my sails to suit the conditions though from my first test the other day I wonder if an adjustable outhaul might be the most beneficial mod to try?
Bynorth sea Just a word on those heavy duty hose clamps
That one you have there looks the same as the ones available here. Made in Spain with a 7mm thread??? that has a very sharp profile that has a strong tendency to galling. S/Steel tends to gall in the threads anyway but these more so
They have become something of a legend here
Anti sieze on those threads is essential
cheers Hiko
Select to expand quoteHiko said..
Bynorth sea Just a word on those heavy duty hose clamps
That one you have there looks the same as the ones available here. Made in Spain with a 7mm thread??? that has a very sharp profile that has a strong tendency to galling. S/Steel tends to gall in the threads anyway but these more so
They have become something of a legend here
Anti sieze on those threads is essential
cheers Hiko
I second that!
Hi all,
Bynorthsea , is that Fraisthorpe beach in the picture ?
Not sailed there but did a bit of kite buggying there last year.
I sail at mappleton,nice easy beach access , a fair few dog walkers but head down to cowden and aldbrough and its not to bad.
My build is not as sleek as yours,more a kite buggy cut and shut , but it does the job for me.
I just changed my windsurf boom for a more standard single boom which i think works better for me.
I am only learning but loving it so far.
