Thread: Quick Canoe Sailing Potential - No such thing as bad questions

It would have been a thrill sailing on those broad reaches.

If you sailed a few broad reaches it means you had to go upwind as well ... what is your report on that? I've certainly found with BETH that going upwind is the point of sail you are least likely to go over on if you have a sailing background - it is pretty easy to keep things in balance.

The capsize report is very interesting.

The only real comment I have is with the halyard cleat.

Quite often plastic cleats have a hole through their base. I thread the halyard through that hole and tie a knot in it so it can't pull through, before hoisting the sail.

That way it can almost never escape.

Otherwise I think the report is about as good as I can imagine for a boat that is so narrow and potentially tricky.

I am very impressed you managed to get the sail back up again while afloat. I think some of this comes down to a sense of balance from all your years of canoeing. A new sailor might have a problem.

So the caveats are avoiding cold water, avoiding big fetches where the waves might get up and have buoyancy bags fitted - or built in buoyancy.

The boat must have looked quite a sight - such a tiny thing and galloping along.

Best wishes
Michael

MIK,

Sorry for the delay. I missed seeing this. Will measure in the morning and report back.

Cheers,

Paul

Didn't need to await the morning. The center of the partner is 18.5 inches in front of the center of the boat. Moonlight was not bright enough to see the millimeters.

I'd need daylight and an assistant to measure for sure but it looks like the mast step is directly below the partner. I made it adjustable although it takes a drill and screw-gun to alter the rake via the step. I did move the step aft to get the mast raked a bit forward of my starting point back while I was sailing her rudderless.

Great tip about the halyard keeper. Next cleat I make for it will have a hole for that.

This week I will be showing off the boat at James Madison University Commons as part of their International Week. Then the next weekend am planning a trip to St Michaels, MD for the Mid Atlantic Smallcraft Festival at the Chesapeake Bay Maritime Museum. I expect it to be one of the crudest looking boats there but I've got her tweaked up to hopefully get some grudging respect due to her performance.

Chesapeake Bay ... I only saw it from the train when I was in the USA. Great that you are getting out and about!

I am part way through doing the mods to cover your larger sail option and stiffening up the standard spars. I will be using your comments and videos when I put it all up on my website. Also will probably put a link in there to Ed Maurer's Canoe sailing web mag.

MIK

ok, more questions.... been off the net for a while (I've been laid up in bed for 4 weeks... , so I've saved a few up.... some off which may be pain killer drug addled )

An international canoe design I've been looking at has a freestanding mast. It uses carbon to line the body, a tube embedded to the hull (with lots of supporting fibre, a timber base, and epoxy), and then a small deck to support the top of the tube.
The mast drops into the tube, with a nylon washer at the top, and a pivot pin at the base.

This got me thinking... what I dont know about is the value of adding glass tape as a means of adding strength.
Previously MIK replied "that the threads of the tape cross the join in the plywood. so the load is transferred from one part of the boat to the other"... understood.

HOWEVER... is there a mechanical strength to be gained by, for example, adding glass cloth between two layers of ply?
Would this make it stronger than the two layers of ply glued together?

No - it is weaker. The reason is that cloth has a "peel strength" - that you can pick up a corner (in theory at least) and pull the cloth out of the epoxy matrix. All the load you put into the cloth is loading up the line along where the cloth is becoming unstuck.

Two pieces of wood don't have the same problem, but by putting cloth between you introduce a mode of failure that was not there when the glass was omitted.

It is even more silly if it is between two layers of ply.

The reason to introduce glass into some sort of layup is to prevent the timber from splitting. Ply won't split - along two of the three axes and adding the glass doesn't change it.

I do know that Boeing is now using glass between two layers of thin aluminium for its airliner fuselage plating, but there it prevents the aluminium from tearing if there is a birdstrike or other impact. But plywood already has that built in resistance to tearing that the fibreglass would provide. If you have played with an aluminium can, you know that it is pretty easy to tear apart. Some glass fibres would change that.

Wood can split, which is why we laminate it to other bits of wood or plywood (or make it into plywood) or why we put glass on the outside. Try and tear a bit of plywood like an aluminium can!

It wouldn't be an American boatbuilding website you are looking at? They really struggle to understand lightweight wooden boatbuilding; we would struggle too but we had almost an extra thirty years of timber building of very high performance sail craft that we all learned from.

One of the boats in the Duck Flat School I have been teaching at was a little strip canoe featured in woodenboat a few issues ago - they had glassed all the inwale and gunwale and keel in the article - I've seldom seen any of these bits split off any boat - and it is way more complication and messiness to the building. Also if a glassed section like this gets hit you end up with a complicated repair to both glass and wood - repairing a wooden gunwale is easy and quick.

The little canoe in the article also used carbon fibre rather than cloth on the inside of the boat. I don't know what loads they were expecting this 11ft paddling boat to experience (and it is irrelevant because the out layer was still normal glass so would pack it in before the carbon was stressed much, but the 2oz normal glass cloth we used on the one built at duckflat would have been half the weight and used half the resin.

With bigger boats I get round the gunwale splitting problem (the way the wood is weakest) by putting one single permanent fastening at the front and back ends of the gunwale. They then cannot then begin to split - but the approach isn't warranted for an 11ft canoe and the glassign approach is never warranted in that case.

There are good places to put fibres to prevent splitting - you see glass tape around the ends of my spars for this reason - but only exactly where needed and it is easy to do. I think of all the added labour of covering, resining and sanding down the glass on gunwales and my eyes cross.

It is also the function of the glass over strip planking - prevent splitting and provide a sandwich to take transverse loads.

With our Mk1 PDRacers we supported the mast at the partner with a block of wood that was moveable on the deck - just in case we needed to adjust the mast rake. This had plywood stuck to the bottom of the block before we cut out a hole for the mast and covered with glass on the top face. But it is a place that experiences very high loads. So we created a sandwich in effect. It also would have been valid to put glass on the underside, but using ply was much easier and simpler. So glass on the outside only.

Bruce has been talking to me about a friend who is wanting to build a Paper Tiger catamaran - he sent me a whole bunch of pics of one with lots of carbon used inside - and it is very bizarre where they have decided to use the carbon - the boat also ended up being several kilograms overweight.

Using glass or carbon or whatever has to be part of a considered approach and understanding of the possible failure modes. If you identify the failure modes properly then the modification can be very minimal.

Hope you are feeling better! I was a bit shocked to see you disappear like that!

Best wishes
MIK

Ouch, a rebuilt ankle. Talk about a highly stressed system!
Hope you are whole again soon.

Paul, yes, a reconstructed ankle is a bugger.
Each replaced ligament is terminated into a hole thats drilled into the bone, and a screw chucked in to hold the ligament in place.
When the pain in the ankle settled, the calf muscle decide to go into a permanent cramp.
Worse was I expected to be able to do stuff around the house, but after 4 weeks I still can't do much more than sit up and elevate the leg... I planned on rehabbing a heap of tools and making a few and some other stuff.

Mik:
here is the IC home build plan and a pic of the mast 'tube' is attached.
I don't think it fair to comment/debate/criticise the design's 'pro's and con's' as the designer/builder can't join the debate, put forward his reasons and thought processes, also... he designed it, built it, raced it and sold it on and it continues to race. In that aspect, it is a complete success.
If he were a professional designer/builder making a commercial go of it, then it would be a different matter.

I've mostly been thinking about this as I deviated from MIK's plan with the decks. I just used a fillet of epoxy bog to glue in the deck to inwale, and the deck does not extend to where the inwale meets at bow/stern. So, wholly held in place with bog.
The deck sits inside the inwale, and about 3mm down, at the bow it is just bogged with a fillet top and bottom; the stern is the same but the bog extends 3mm thick across the whole deck on the top, with a 3x the ply fillet underneath.

So far the rear deck has held up fine.... when I'm better I'll test the strength better.
The front deck fillet failed where I went a little thin when I sanded back, and I decided to take it out and add an inwale scrap under it as per MIK's plan.
When I tried to break the fillet with a thump of the fist, the inwale timber split... on the side with a good bog fillet, the ply/bog was stronger than the hoop pine inwale.
I'll add that the break was caused by a 60kg person treading in the middle of the widest part of the deck, to exit the canoe.

So, I thought that next time, I'll drill the inwale, heat and try to impregnate the inwale with epoxy where it meets the deck - to strengthen the hoop pine; and add a 3x ply fillet under it
with a greater fillet line between deck and inwale.
Or I could stop stuffing around and just follow MIK's design and take the tried/tested/well reasoned and 'correct' approach.

I'd rather learn from failures and stuff around though... that way leads to some kind of understanding.
Hence, I've been trying to learn the concepts behind material strength of ply/epoxy/cloth and whatnot.

MIK - as usual, a comprehensive and clear answer..... thanks!

MIK - in Paul's 'drop in sail thread' you said:

Between you and Clinton it almost needs a pure sailing version with permanent mast steps and buoyancy tanks

YES.

or sit back and watch my ridiculous efforts and spend time laughing.

Bouancy bags in AUS is annoying me. One of my house bound activities was going to be an attempt to find a way to make them cheaply, at home.
I see no reason to spend as much on bouancy bags as the entire canoe... and fitting enclosed cell foam or polystyrene into the deck cavity is nowhere near as elegant as bouancy bags. When I am mobile its my next project...

I am thinking of modifying my qc to have rails that allow a seat mounting or a mast step, (and another set that allow the fitting of an extended deck for the 'top of the mast support tube') depending on intended use, but my knowledge is too basic to do a good job first time.

I would greatly appreciate your efforts into a qc plan for a sailing version.

Originally Posted by Clinton1

Mik:
here is the IC home build plan and a pic of the mast 'tube' is attached.
I don't think it fair to comment/debate/criticise the design's 'pro's and con's' as the designer/builder can't join the debate, put forward his reasons and thought processes, also... he designed it, built it, raced it and sold it on and it continues to race. In that aspect, it is a complete success.
If he were a professional designer/builder making a commercial go of it, then it would be a different matter.

In a way that's true, but also if you ask me to make a comment to explain it - I have to write something. Also I do look at things closely to see where it fits within the framework of what has gone on before.

I can't see how having the glass in there makes any difference - but thanks for the link to the original article.

If I knew the international canoe was designed by Phil Stevenson - who is well known in Moth circles - I might have been a bit less opinionated, but I still can't see any reason for the glass being there - particularly if it is sandwiched between two pieces of ply.

Anyway ... hope you found what I said a little bit useful.

In a way my theme in my reply is that lots of people are starting to stick glass all over the place with little reason to do so.

Phil only uses a tiny piece - the one I find contentious - and looking at the rest of the structure, there is not a lot of wasted material - it ain't bad at all.



All boats go through a refinement process - It will be interesting to see the changes if he keeps developing it over the next few years.

For example the sheer clamps and rudder case headlogs look like about 19mm square - the Moths in their plywood hey-day would have had it down around 12mm square - though you might need a tad more because the carbon carries more load. Consider that by going from 19mm square to 13mm square halves the weight.

These tortured ply international canoes are all relatively new boats and it takes quite a few years for them to get round to their ultimate form. Note too that this page dates from 2006 - probably the build is five years ago now.

Phil has also been a huge supporter of wooden construction for raceboats in general - so well worth looking through what he has written on that website.
There is also more here - moth based.
http://www.moth.asn.au/download/buil...h_hardware.pdf
http://www.moth.asn.au/download/buil...skiff_moth.pdf

Best wishes
Michael

MIK, your 'opinionated' reply was based on my question as to the reason for adding cloth between ply.... as such, the answer was based on that and not on anything else... and was a very good answer. Thanks for adding to my knowledge about the peel factor.

Your comment about Phil's design being a '06 one, and experimental was on the money, and involves my comment about not wanting to speak about his design.
I've no idea why he made his decisions the way he did, or what he was testing versus what he was assuming in his design... and what he knew from past builds.

For those reasons, I don't want to invite comment on his design... its part of an evolution, which involves the currently 'dark art' of stressed/tortured ply.

In short, I'm looking at his design, and realising just how ignorant I am, and trying to fix that.

Soooooo.... if cloth between ply (or timber) adds no strength due to peel factor, and if I want to add strength to the the ply to gun/in wale then I guess that I should:

a) run my rebate plane (with a v or u blade fitted) down the timber to create a v or u shaped rebate, as well as chamfer top and bottom edges of the gun/in wale so the bog has a fillet area; or

b) run my scraper down the timber with a toothing blade fitted, and chamfer the edges' again for the bog.

in other words, create a greater bonding area for the 'poxy bog, just like I'd do in an epoxy bog based furniture joint.

is this correct (time/effort analysis aside)?

Originally Posted by Clinton1

MIK - in Paul's 'drop in sail thread' you said:
Bouancy bags in AUS is annoying me. One of my house bound activities was going to be an attempt to find a way to make them cheaply, at home.
I see no reason to spend as much on bouancy bags as the entire canoe...

Cask wine & water bladders.
Put them inside a buoyancy compartment or a fertiliser sack and tie it in.
cheers
AJ