Thread: BETH -YuanFen- Building a wooden sailing canoe in Poland - Budowa drewnianej kanadyjk

Howdy

Robert's nice drawing had the outline of a perfectly flat sail. The right allowances for the spar bends with medium wind downhaul tension (quite a lot) applied.

However, with this setting we want to have about 8% camber - depth of the sail divided by the width at each point along the yard. A less narrow boat might use 10 to 12% camber.

Anyway to get the depth you add more sail to the curve along the yard. It worked out that to get the 8% the distances along each of the thin red horizontal lines across the sail had to be increased by 1.68%. I worked out the percentage with the arc drawn to the right of the sail.

This is not quite as good as a properly constructed sail where all the seams have some shape in them, but it is not too bad either. And will cost less than 7% of a professionally made sail. I am hoping after a season or two of use Robert might decide to give Beth either a sail made of proper sailcloth or even a professionally made one.

Hmm Robert, wonder if you want to use the cool new RAID41 type of boom for Beth and carry the sail loose footed? ie not laced along the boom ... allows a lot more depth to be put into the sail quickly when reaching or medium winds when you are looking for more power. The original boom is a bit flexible to be used loose footed.

It is possibly not as pretty as the original Beth rounded tapered spar.

MIK

Originally Posted by Boatmik

I am hoping after a season or two of use Robert might decide to give Beth either a sail made of proper sailcloth or even a professionally made one.

I'm hoping too

Hmm Robert, wonder if you want to use the cool new RAID41 type of boom for Beth and carry the sail loose footed? ie not laced along the boom ... allows a lot more depth to be put into the sail quickly when reaching or medium winds when you are looking for more power. The original boom is a bit flexible to be used loose footed.

It is possibly not as pretty as the original Beth rounded tapered spar.

That's interesting proposal! Can I see that one somewhere?
Possible to use slab reefing with loose footed sail will be too???

Today I've prepared knees which were cutted off not quite accurate:


At present they are almost ready for assembly (they needs marked deck camber, marked and cutted notches for chinelogs and sheerclamp... - soon, I hope so)

Hi Robert,

How do you write "Building a wooden sailing canoe" in Polish?

I will send you the drawing of the boom, but now I have "slept on" the idea I think that the original round boom and lacing will look the best.

And BETH is 90% about appearance.

(actually that is not fair .. she is 80% about performance too!!!)

MIK

Originally Posted by Boatmik

How do you write "Building a wooden sailing canoe" in Polish?

It's VERY strange and difficult ...

"Budowa drewnianej kanadyjki żaglowej"

It's curious than "Kanadyjka" means "Canadian woman" and "kanadyjka" means "canoe"

At present you can read about "Building a wooden sailing canoe Beth -YuanFen-" in Polish there:

http://sailforum.pl/viewtopic.php?t=6886

and there:

http://groups.yahoo.com/group/michalak-polska/

I will send you the drawing of the boom, but now I have "slept on" the idea I think that the original round boom and lacing will look the best.

And BETH is 90% about appearance.

(actually that is not fair .. she is 80% about performance too!!!)

Yes Michael, she is beautiful as designed!
But I'm interested in experiment with sails - I consider to use slab reefing system modelled on old systems used on sailing canoes from 1880 - for example:

http://dragonflycanoe.com/stephens/

...like those:







... etc.

Sounds like we might get a lot of Polish men who are not looking for canoes, but hot Canadian women!?

I did get a whole bunch of reefing grommets put into the sail intending to try the systems that have ropes going up and down the sail. However I did find that simply tying the ends down and not tying down the middle was quick and effective. However .... it is nice to be able to pull down the luff without leaving the cockpit!!!!

Found it was fastest just to pull the mizzen on so the boat sat head to wind, ease off the downhaul, drop the main, tie the two reefs in and rehoist the main and retension the downhaul.

The battens also do reduce the power of the sail quite a large amount.

I think the ropes from the battens around the mast to hold hte mid part of the sail against the mast reduce efficiency too.

MIK

Hi MIK and Robert

I have two battens in my mainsail. Very cheaply bought from my local sailmaker. I had a look at my windsurfing sails in my garage and noticed how the battens are thinned down at the leading edge to form a really nice aerofoil shape when loaded up.

I have reefing grommets at both ends and two small reefing 00 grommets on each batten to tidy up the sail when reefed.

I am interested to see what practical, easy to use reefing lines work out best. The RAID41 L shaped boom also has promise for including lines under the "shelf" of the L shape.

For instance a line from the reef grommet, down through a hole in the top shelf, once around the boom, and along to a hook would make a very quick reef pennant. Could be used at both ends of the sail. Nice to drop the sail, work at the mid point of the boom and pull down both pennants to hooks under the boom? Similar for the second reef?

What do you reckon? Need to do something soon for Trim.

Brian

Originally Posted by Boatmik

Sounds like we might get a lot of Polish men who are not looking for canoes, but hot Canadian women!?

Yes indeed

I did get a whole bunch of reefing grommets put into the sail intending to try the systems that have ropes going up and down the sail. However I did find that simply tying the ends down and not tying down the middle was quick and effective. However .... it is nice to be able to pull down the luff without leaving the cockpit!!!!

Found it was fastest just to pull the mizzen on so the boat sat head to wind, ease off the downhaul, drop the main, tie the two reefs in and rehoist the main and retension the downhaul.

Probably - simpler is better!!!

But... Possible is to crawl (to creep) by the fore deck to the mast for tie reef knot on fore end of the boom? Is Beth stable enough? Hoping she is
" it is nice to be able to pull down the luff without leaving the cockpit!!!!"
it is safer!!!

The battens also do reduce the power of the sail quite a large amount.

I think the ropes from the battens around the mast to hold hte mid part of the sail against the mast reduce efficiency too.

Battens can reduce camber a bit - it would be good in strong wind only.
Ropes produces turbulences and resistance - it's not good, I agree.

Originally Posted by robhosailor

Battens can reduce camber a bit - it would be good in strong wind only.

As a very experienced windsurfer I am not sure about battens reducing camber. My sailing canoe, a MacGregor did have flat battens which would have the above effect. However my windsurfing sails, still stored in my garage, have camber induced by sail tension even in zero wind. Take a batten out and just press it against a wall and the most amazing shape appears, a terrific foil sectional shape.

Quite how such a batten might behave when used in a lug rig set on the windward side of the mast I don't know, but soon will!

Brian

Originally Posted by keyhavenpotter

As a very experienced windsurfer I am not sure about battens reducing camber. My sailing canoe, a MacGregor did have flat battens which would have the above effect. However my windsurfing sails, still stored in my garage, have camber induced by sail tension even in zero wind. Take a batten out and just press it against a wall and the most amazing shape appears, a terrific foil sectional shape.

Quite how such a batten might behave when used in a lug rig set on the windward side of the mast I don't know, but soon will!

Brian,
Probably you are right in windsurfer sails - battens (flat) and sails are designed as a compatible system with tuning ability - you can set (adjust) tension and camber for permanent (in your garage too) in zero wind .

Traditional lug sails and battens a bit different I think so* - but... if battens are flat and/or tappered with similar tuning abilities (adjust) of sail's camber...

I've seen couple of photos and drawings of lug sails (I have not my own experience in it) with battens and with no battens:
When sail on windward side of the mast - with battens camber is flat or smooth "S" shape or can be reverse too. Without battens sail's profile is demaged by mast often like this:



Which is better?

...
*) Traditional - timber or bamboo battens

Originally Posted by keyhavenpotter

Hi MIK and Robert

I have two battens in my mainsail. Very cheaply bought from my local sailmaker. I had a look at my windsurfing sails in my garage and noticed how the battens are thinned down at the leading edge to form a really nice aerofoil shape when loaded up.

I have reefing grommets at both ends and two small reefing 00 grommets on each batten to tidy up the sail when reefed.

I am interested to see what practical, easy to use reefing lines work out best. The RAID41 L shaped boom also has promise for including lines under the "shelf" of the L shape.

The new boom is an inverted L shape for use with loose footed sails. With NS14s (similar to Merlin Rockets but freer in restrictions) we used T section timber booms as they resist bending very well and use the high tensile strength and lower compressive strength of timber in a clever way.

Merlins are a good comparison, the USA has been very much more one design oriented, so I can't think of anything that relates there.

I started of by thinking of a T shaped boom for the RAID's loose footed mainsail and was working on building in a pad so the T could rest against the mast. Then realised the whole thing was easily achieved by moving the top flange across to make an inverted L. I think this will become the standard boom for performance luggers around the world - it even saves labour!

But as I pointed out in Robert's BETH thread ... it is not as pretty.

For instance a line from the reef grommet, down through a hole in the top shelf, once around the boom, and along to a hook would make a very quick reef pennant. Could be used at both ends of the sail. Nice to drop the sail, work at the mid point of the boom and pull down both pennants to hooks under the boom? Similar for the second reef?

What do you reckon? Need to do something soon for Trim.

Did I send you my fittings list so far .. have a saddle at the front end of the boom for the sail to lash or shackle to.

Reefing line can go from saddle, to cheek block on side of boom back to mid boom. I don't think it needs to go around the boom at all.

MIK

Originally Posted by keyhavenpotter

As a very experienced windsurfer I am not sure about battens reducing camber. My sailing canoe, a MacGregor did have flat battens which would have the above effect. However my windsurfing sails, still stored in my garage, have camber induced by sail tension even in zero wind. Take a batten out and just press it against a wall and the most amazing shape appears, a terrific foil sectional shape.

Quite how such a batten might behave when used in a lug rig set on the windward side of the mast I don't know, but soon will!

Brian

Howdy,

There are a couple of things that help create camber in sailboard sails - the convex roach and those wily camber inducers.

Forgetting the camber inducers for the moment ...

The battens operate as a column in pure compression, however as the compression load on the end increases they suddenly "cripple" - they suddenly bend and cannot resist the compression force any more so buckle in the classic engineering mode. The sail they are tied into prevents them from bending more.

(the engineers and Alex are with me now, because he is reading the books by J E Gordon which covers this)

However ... with the lug rig there is no convex roach to forcefully cripple the battens.

I tried a whole bunch of tensions and one day I arrived at sailing and one of the battens in BETH's mainsail had broken. So reluctantly I took them both out and went sailing.

Felt like the turbo was on!!!! Probably about 20% more power. Also less effective distortion around the mast .. I suspect the air reattaches to the leeward side a bit easier too. because the sail just has a very local dent from the mast rather than the batten spreading it out.

If you have the pockets .. it is easy to experiment. There might be some configuration that is useful, and I would use battens going on a cruise.

Best wishes
MIK

Originally Posted by robhosailor

Brian,
Probably you are right in windsurfer sails - battens (flat) and sails are designed as a compatible system with tuning ability - you can set (adjust) tension and camber for permanent (in your garage too) in zero wind .

Traditional lug sails and battens a bit different I think so* - but... if battens are flat and/or tappered with similar tuning abilities (adjust) of sail's camber...

I've seen couple of photos and drawings of lug sails (I have not my own experience in it) with battens and with no battens:
When sail on windward side of the mast - with battens camber is flat or smooth "S" shape or can be reverse too. Without battens sail's profile is demaged by mast often like this:

The damage to the sail's profile on the "wrong" tack is something you can't feel much at all. Both of you guys will be able to feel it a tiny bit because you have spent enough time racing. However it doesn't seem to be a very big factor - when I was racing BETH against Lasers I didn't lose much on the "bad" tack.

Which is better?...
*) Traditional - timber or bamboo battens

It probably doesn't matter too much Robert. I would suspect that the bamboo would chafe the sail more .. abrade the cloth by friction because of the bumps.

But no particular prejudice against bamboo. PVC electrical conduit can work too. But the wooden materials are nicer.

Great discussion chaps! So glad to have you all here!

MIK