Plank-on-frame virgin no more..

Hi guys, Yes I’m still alive!
Just thought I might share some pics of my latest baby…3 evenings build time down the line, my first attempt at plank on frame…
The boat is for a university project, to a 70cm rating rule for a inter-course race on the 1st of june…If it looks a bit like an ACC boat thats no coincendence. It has to be freesailng too so no r/c this time. It will have a wingmasted schooner rig so if it comes last I’ve got an experimental rig to blame!
Yes, I’m gonna be spending a long time fairing.

Welcome back Matthew. :nuts:

An interesting looking project which we shall follow with interest.
I am not sure if we really need to know that you have lost your virginity and you are to have an intercourse race shortly, too much information I think.:sing:
(just me being silly) but seriously do keep us all informed.
Good luck mate.:fish:

not even a multi from our “boy”…pfff

Nice one…hope will continue to show us your work

Well, been a while, but here you go. Sails pretty nicely!

The boat looks great. and even sails good. by the looks of the pictures. congrats my friend. i told you it was not that hard. opppps did i say that. :spin:
i am having my own problems with my IOM and planking:magnify: i think that is the trouble. could be just my eyes:icon_smok
like the pictures of her in the water

Hey Matthew, that looks like a lot of fun.
Mate, we need some intimate details on that rig. Looks a little different…:idea_125:

Have you had your race yet?

That rig…well its a unstayed-wing-masted-gaff-rigged-cat-schooner…!
Bit of an evolution of the last few rigs i’ve built, and it cheated me a pile of sail area from the rule as mast area is ‘free’ area, as was roach area till a lecturer saw my design and said 15% roach max (distributed as you like, hence the masive roach on a ‘short’ rig, the rule max mast height was 1.3m, mine is 1m.). I chose a schooner as it would be easy to balance the rig, and cat rigged as I couldn’t get any free area out of a jib. And anyway, I had to be different! Race is next week…We shall see…

Your wingmast rigs caught my eye too. Looks great!! They appear similar to the concept I’ve been playing around with. Could you tell us a bit more about the construction details?

Well, they’re pretty simple really. The masts themselves are just balsa shaped to a rough airfoil shape, I found a balsa section in the local model shop that made this easy, think its for the flaps on model aicraft, anyway I glued two sections back to back to increase the chord and trimmed down the leading edge and rounded it. Then I cut a slot and epoxied in a 8mm carbon rod to work as a mast base.

The gaff is a carbon rod made using Doug’s silicone tube trick (like the guy or not, that trick does work and its the best way of making a model square top rig work imho). The boom was made again by pulling carbon fibers through a silicone tube, using the loop of fibres at the end round a 8mm inside dia carbon tube to make the boom pivot.

There is no vang and the leech tension is controlled by a strop across the top of the boom and the clew downhaual and peak uphaul. Rotation of the mast is controlled by the outhaul, although mast spanners could be fitted.

Improvements; well balsa mast is a little heavy (shade under 100g per stick, 1m long) Was going to make foam and carbon ones but ran out of time. Also the masts dont tack all that well, could do with wearing in a bit.

The balsa aileron stock is a good way to start & you can always build a lighter composite mast later when the design is finalized if needed.

I see what you mean about the mast tacking issue. In a couple pictures, the masts appear to be “under-rotated” which will kill any gain in aerodynamic efficiency. If anything you want the mast to be a bit over-rotated to induce full draft/camber in the soft sail & give a “fair curve” for good airfoil shape.

Are the masts free to rotate independent of the boom angle? Does the “strop across the top of the boom” somehow impede rotation? Perhaps a bit of lubrication in the pivots would help? One advantage of stayed rigs is that you can use an extended hound attachment to act as a lever arm, ensuring full rotation:

The lack of rotation purely comes from friction, the third pic has both masts on the wrong tack and the boat sails like a dog. When i get the boat back tuesday I’ll suss out how to sort it.