Leeboard core material choice

Hi there, I stumbled upon this website while trying to decide which core material to use on a future project. It will seem rather tiny compared to pretty much every other project I saw in this forum! Basically I have a Canadian style open canoe and have a sailing rig for it already. I would like to build a leeboard something like thosw found here - Accessories https://www.solwaydory.co.uk/products/accessories/ but I was thinking of using a lighter material and then fiberglassing over it. I don't want to break the bank but would prefer to build something lighter than using marine grade plywood, which would also require less maintenance as I know I'm not great at keeping up with that sort off thing - I'd rather just spend a long time once at the start and have it last a really long time. I don't think that the little sail on my canoe will produce as much sheering force as the craft you guys on here are used to dealing with, but I'm really not an expert. I was wondering about using balsa, PET foam, PU Foam, PVC foam or Cedar laminate. I basically want it as cheap as possible while still withstanding the sheer forces and weight being a secondary concern as long as it will be lighter than using marine ply. I hope this makes sense!

I'd appreciate any input with all the experience I've already seen in the other posts in the forum already.

 

Bernd Kohler is an innovative designer who simplifies construction techniques for home builders. A "best bang for buck" type of person and quite successful at his work.

If you don't want to use ply you will have to keep looking, but marine ply can be easily treated so that longevity can be expected. End grain in ply is where most issues occur.
How to Build Rudders or Dagger Boards https://smalltrimaran.co.uk/how-to-build-rudders-or-dagger-boards/

 

Re the Solway Dory leeboards, would you prefer something like the longer Pivoting Leeboard, or the Expedition Leeboard?
Both are made from hardwood, and I am thinking that this is probably also the best material for you to use as well?
It would certainly be much easier to get a nice aerofoil shape using solid timber (or even plywood) rather than trying to build an aerofoil using a foam or balsa core, and then glassing over (and fairing) it.

 

Go to the hardware store, buy some generic SPF (aka. white or redwood) without knots and tight grain. Simplest if you buy some PAR battens, those usually have the best quality, then you glue them into a blank and carve your shape. Actually any free wood will serve, even broken pallets or firewood, it's just more work.

As for beeing lighter then marine ply, it depends on what you compare exactly, since there are several species of wood marine ply is made out of. Obviously the whole thing is academic, because of the size of the finished piece the weight difference between the heaviest and lightest marine ply or solid wood you can reasonably be expected to find will hardly be more then ~1.5kg.

 

I agree with Rumars,but would add that if you believe you will still own the boat in five or six years it might be worth the time and effort of glass sheathing the board with a light glass cloth.For a shorter likely ownership it may not justify the extra effort.

 

Thanks for this reply. Yes, the more I look into this it is looking like a hardwood will be the best option. I live in Northern Ireland so something like larch should be easy enough to find for a good price. I am thinking of going more towards the longer pivoting leeboard style, possibly adding a hole to the end of the handle to allow for attaching a bungee cord and a regular cord - to pull on the regular cord and cleat it off to raise the board and the bungee would drop it back in when it's released.

 

Thanks Rumars. I am looking into what hardwoods I can get at local hardwear places, sawmill and builders merchants now. If I can get a single board with the right dimensions I'll go that route, but if not then the PAR battens glued together is a good idea too, thanks.

 

Thanks Wet Feet. I intend to have this boat (or another almost identical boat if I can ever financially upgrade to a better one) for as long as I am still able to use it. So I am definitely going to glass it at the end of the process.

 

I am wondering a couple things.
-If making the 'cricket bat' looking leeboard, would the handle piece be better as hardwood and then the leading and trailing edge could be a softer/lighter wood for foiling?
-Would a foil with a flat section also facilitate the manufacturing and bearing against the boat?

 

This could definitely be a good option, thanks!

 

Cedar or redwood.

you’ll really want to sheath most anything to prevent warpage

 

Unfortunately northern irish home depot equivalents don't stock cheap WRC fencing boards.
The usual domestic softwood choices are "whitewood" (spruce and true fir), "redwood" (pine), douglas fir and larch. Hardwoods are ash, oak, beech and chestnut.
Funny enough, imported hardwoods can be cheaper then domestic ones, for example right now haldane fisher sells 12x44mm sapele for 3.71£/m and the same in oak is 6.48£/m. Same dimension in PAR "whitewood" is 0.91£/m. Material for a 1000x200x44mm board would be: oak 110.16£, sapele 63.07£, whitewood 15.47£. If he uses 19x44 sapele total cost is 56.32£ and with 44x94 whitewood its 10.34£. If I go down one step, general carcassing whitewood 47x200 is 6.49£/m, you just have to go trough the entire stash to find a knotless one with good grain.
For a nice two tone board with a handle, combine two pieces of sapele for the middle part where the handle is with whitewood wings, total cost something under 20£.
Or, as I said, go by some construction dumpsters and get the wood for nothing. If you're lucky you might even score some nice colored hardwood from old flooring or furniture.

 

Thanks Rumars, this is looking like the best option. I also have to make a brace/bracket to attach the leeboard to the canoe on either the carrying yoke/thwart, or to the gunwhales, or a combination of both. Would I be correct in ruining that I'll need a hardwood for that too? The thwarts on the canoe are made from Ash, so I could maybe use the same?

 

I would recommend you make an aka with an epoxy glue up for the bracket. It can cross where desired. I would glue something on the order of 3 pieces 10-12mm thick by about 2” wide. Then you can tied that to the gunwhales using rubber lashings.

 

@Rumars is right. I started to go down a list of the different foils I've made but that's not helpful if you're needing a leeboard for a canoe.