Inspired by this 19 page seabreeze post www.seabreeze.com.au/forums/Windsurfing/General/Division-2-board?page=1, I decide to build a Lechner A390 division 2 sailboard. I was also interested in learning how to go about building a hollow windsurfer. I've finished the board and sailed it a handful of times and really enjoying it for 5-15 knots.
Being hollow it was quite a complex build process and you can read more about it at infinity1971.bitbucket.io/
That's really cool. Looks like a stressed skin with pretty substantial bulkheads. What made you settle on 150mm spacing on the bulkheads?
Wow that is a lot of hours and that is very impressive and love the link to the entire process.
Well done and enjoy "upwind on the rail" 
So glad I clicked on the link and took a look. Well worth it. Absolutely a labor of love. Hope it brings you many (more) hours of joy.
What a lovely piece of work. I too would be interested in the weight.
The Lechner is lovely. Have you got a good tight leach deep draft racing longboard sail? They work dramatically better than a "modern" shortboard sail on a longboard, and particularly on a Div 2 board.
Select to expand quoteaeroegnr said..
That's really cool. Looks like a stressed skin with pretty substantial bulkheads. What made you settle on 150mm spacing on the bulkheads?
Thanks aeroengr, The 150mm spacing is for the mould. In the actual board it is generally 250mm spacing (infinity1971.bitbucket.io/#table:board-stations) but with some closer spaced ones on the fin-box and centre-box. For the internal frame I didn't have much to go on so took conservative approach and probably could increase spacing given the stiffness of the skins.
Sandman, Chris, The weight is 16.9kg (infinity1971.bitbucket.io/#sec:weight). I think if I did it again I could get it down to 15kg. The weight relates to aeroengr point about "substantial bulkheads", I deliberately over-engineered the board structure to ensure I had something which I could rely on and would last. Although according to this infinity1971.bitbucket.io/#fig:lechner_facebook_05 the original Lechner was 18kg (hollow too) so 16.9kg isn't too bad.
Chris, I'm using twin-cam freeride sail (infinity1971.bitbucket.io/#testing-the-board). I have the sail below ~1990 and is tight leech, maybe I should give it a go for comparison?
Select to expand quotejonesmb said..aeroegnr said..
That's really cool. Looks like a stressed skin with pretty substantial bulkheads. What made you settle on 150mm spacing on the bulkheads?
Thanks aeroengr, The 150mm spacing is for the mould. In the actual board it is generally 250mm spacing (infinity1971.bitbucket.io/#table:board-stations) but with some closer spaced ones on the fin-box and centre-box. For the internal frame I didn't have much to go on so took conservative approach and probably could increase spacing given the stiffness of the skins.
Sandman, Chris, The weight is 16.9kg (infinity1971.bitbucket.io/#sec:weight). I think if I did it again I could get it down to 15kg. The weight relates to aeroengr point about "substantial bulkheads", I deliberately over-engineered the board structure to ensure I had something which I could rely on and would last. Although according to this infinity1971.bitbucket.io/#fig:lechner_facebook_05 the original Lechner was 18kg (hollow too) so 16.9kg isn't too bad.
Chris, I'm using twin-cam freeride sail (infinity1971.bitbucket.io/#testing-the-board). I have the sail below ~1990 and is tight leech, maybe I should give it a go for comparison?
Thanks! I see, that's really cool. Sounds like you're taking good advantage of a sandwich design. Fun project, and hope you have some great times on it.
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