Thread: Cadet MK2

Originally Posted by meerkat

We've picked up a cadet Mk2 to fix up for our son to compete (and be competitive in) next season. The hull is in good nick but the deck needs replacing.

What is the best way to proceed ?

eg take the deck off as whole pieces to use as templates for the replacements etc.

the foredeck is in 2 pieces should we do the same or make it one piece (if we can get a sheet big enough) etc.

I'll be getting some piccies to show the progress shortly.

Thanks
Andrew

Howdy Andrew,

First thing is to have a look at the class rules to find out what you can get away with.

http://www.cadetclass.org/documents/...0Rules2005.pdf.

For a competitive boat you should use premium materials - gaboon plywood for the decks

Any framing to be replaced should be Western Red cedar - or cheaper and lighter Kirri/Paulownia.

Glue and sealing the panels before fitting to the boat - epoxy. With coating make sure it is rolled out thin so it doesn't add too much weight - three thinly applied coats - but don't thin the epoxy - see my FAQ.

http://www.woodworkforums.ubeaut.com...ad.php?t=28522

Also ee my boatbuilding FAQ for info on wet-on-wet epoxy coating to save some labour and use of cordless screwdrivers for holding everything together while the glue sets up.

There are pics of a lot of the same processes on Midge's Puddle Duck pages.
http://www.woodworkforums.ubeaut.com...ad.php?t=28107

Am in a rush now - but will put more info up later.

oh, yes - deck sheets are best of one piece as far as possible - but can be scarfed or have butt blocks under (we had to repair a sheet on the Puddle Duck Racer thread - scarfs are 6 times ply thickness, butt straps are 20 times ply thickness.

MIK

hi Mik

I read through your FAQs (might I say quite interesting and well put together) and I have a few questions.

Rather than using 2 pt polyurethane you recommened using epoxy with a poly topping (1) is this right ? The coats of epoxy are as thin as you can get them.

So i'm thinking....
the deck has 2-3 coats of epoxy with a coat of poly

inside has the 2-3 coats of poly (unless the epoxy is good there too). The problem with the inside is that there is some drips of epoxy that has been left there from a previous attempt to repair the deck as well as some black lines going across the boat and up the sides(why I dont know). so I'm not sure how that will come out.

The hull will be painted.

Oh yeah, after removing the lid there are a lot of holes left by screws, copper nails and yes even steel nails :mad: that have rusted & expanded and left holes like what screws do !

Whats the best to fill these with and will that affect the nails going back in ?

thanks
Andrew

Originally Posted by meerkat

hi Mik

I read through your FAQs (might I say quite interesting and well put together) and I have a few questions.

Rather than using 2 pt polyurethane you recommened using epoxy with a poly topping (1) is this right ? The coats of epoxy are as thin as you can get them.

So i'm thinking....
the deck has 2-3 coats of epoxy with a coat of poly

inside has the 2-3 coats of poly (unless the epoxy is good there too). The problem with the inside is that there is some drips of epoxy that has been left there from a previous attempt to repair the deck as well as some black lines going across the boat and up the sides(why I dont know). so I'm not sure how that will come out.

The hull will be painted.

Oh yeah, after removing the lid there are a lot of holes left by screws, copper nails and yes even steel nails :mad: that have rusted & expanded and left holes like what screws do !

Whats the best to fill these with and will that affect the nails going back in ?

thanks
Andrew

Hi Andrew,

You probably don't need to put any nails back in. See the FAQs I gave the links to previously about
Cordless drill and,
Eliminating fastenings.

As far as gluing you just need to hold things together while the epoxy sets up - no need for permanent nails or screws.

As far as drips etc on the inside remove them by sanding - random orbit sander is good here - about 100 grit paper - be VERY careful not to cut away at the plywood veneers!!!
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Before committing yourself to lots of epoxy coating it may be worthwhile reading the rules about what is a and what isn't counted in the hullweight and then weighing the boat in that condition.

Also read whether lead (metal) correction weights are allowable and checking whether there are any fitted - remove them before weighing.

The decision tree goes a little like this.

If the boat is much more than 5kg over - it is a short term boat - it will be pretty well impossible to get it down to the minimum. Clean it up just as much as you need to get it on the water. Your son will race it for a year or so and then will start to have enough experience to make a better boat go well. Don't spend too much money on this type of boat.

If the boat is only a kilo or two over it is a good boat if it is ready to go in good sailing condition. Just patch up to keep going, you can't afford to add much weight in epoxy (or anything else) so just two very thin coats. Bote Cote have a product called TPRDA that thins epoxy out without destroying its capacity to protect the timber - use it to the max allowed - roll the epoxy out well spread. Adding thinners to epoxy is not cool for boat use.

If the boat is under weight by a kilo or more - you're in luck. Provided the hull is stiff and fair (the chines and panels have nice geometric shapes - nice even curves, no hollows and bumps) this is the sort of competitive boat that is worth fixing up and giving the full epoxy treatment to.

So weigh it and see what you've got.

____________________________

2 pot polyurethane is only really for finishing the decks off - it gives a very strong surface with a good appearance, you would need 3 coats minimum. As an alternative you can use a good spar varnish as an alternative or paint the decks with a marine enamel.

YOu wouldn't use any of the above inside the bouyancy tanks as their purpose is to give a good appearance..

If the boat is two or more kilos overweight an alternative for inside is to use Everdure - a couple of coats. It is nowhere near as effective in keeping water out of the wood as using epoxy, but it doesn't weigh as much.

Epoxy coating is good from a wood and weight preservation perspective, but it will add a couple of kilos to the hull weight - even if you are careful.

If the boat is going to end up being pretty competitive with that added weight (ie no more than a kilo over minimum) then epoxy is a worthwhile investment - depending on how much labour is involved. Or just add the epoxy as you do work on the boat.
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The most common pitfall is that someone in your position gets all excited about fixing the boat up. They lose track of the fact that the boat is probably pretty close to sailable now. I would suggest doing the minimum you can get away with until you find out how commited your son is.

Another thing is not to overcapitalise an old boat unless it can be competitive - ie close to minimum weight, fair and stiff. Don't add new sails, new masts to an old clunker. Maybe pick up some second hand sails from some of hte top sailors in the class if the ones you have are shot. Replace other things as necessary. Then see how enthusiastic your son is after the first season.

A cheaper and a better way to get a fast boat is to buy a good second hand racing boat that is doing well in its fleet than to completely re-outfit an older boat with new sails, mast, rigging and fittings.

So weigh the boat and inspect it so you know whether it is a goodie.

If it is a bit heavy or out of shape - just do the minimum to keep it going - after the season sell it for what your bought it for and get a current competitive boat.
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One labour intensive but very effective way to lift performance is to make some highly accurate and smooth foils - rudder and centreboard. They can then be moved onto a new boat when the time comes.

Shape is important so you have to use templates - contact me on
[email protected]
if you are after templates and an instruction sheet.
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Sorry this is a bit rambling - trying to cover a lot of ground

hi Mik

thanks for the info it is really appreciated. This is my sons first complete season in the cadets and is looking forward to many more.

The minimum hull weight plus fixtures (not loose items) is 54kg.

The boat less fittings and the deck is approx. 45kg. No additional weights are in the boat as it is.

So adding the deck and fittings (I estimate 2kg) and a kg as buffer I'm looking at about 6kg spare.

based on this I think it's a goer for a half decent job. I'm currently stripping the 6 or so layers of paint off the hull (I don't like the colour for some reason.

My aim is to fix only what needs fixing, repaint the hull, replace the dud fittings and to get the lid replaced. The sails are in good nick and the mast/boom are quite reasonable.

I will however need to look at the centreboard and rudder though. They have seen a little work

Thanks
Andrew

Finally got some pictures to the right size.

The first three are what we started with.

The fourth is with the lid off.

Currently taking the paint off.

You have done very well with selecting the hull! It sounds like a keeper!

Epoxy is the go and will give it a good racing life.

Gaboon ply decks in the thinnest allowed by the rules.

The join in the decks is in the right place for most economical ply and the foredeck mid stringer is wide enough for both to land on.

If you are removing the paint you'll probably have to replace the glass tape on the chines too. See the puddle duck racer thread for where the bottom was coated and the glass tape whacked down at the same time. All happens in one process - wet on wet. Glass tape 50mm wide. Don't round the chines too much - existing amount will be OK - but you want the last 3ft of the chines and transom corners dead sharp for clean water release - best to have a round there for the fibreglass tape to go on and then bog it out to a sharp edge with epoxy/filler powder mix.

Sounds like the hull is a good basis for improvements of sails and rig later on - but the first season with the existing ones.

There are probably some Cadet tuning guides on the net that may have things that you can do at this stage and also things like fittings placements on deck. You may need to work out where fittings will end up and glue the smallest possible pieces of 9mm ply (gaboon as well) under the decks to screw the fittings down to where you can't use bolts (all bolts should be Nylock heads - it costs a bit more but adds hugely to the realiability of the boat.

Any screws or bolts should be dipped in epoxy to prevent water getting into the hull and it also increases the grip of the fastening manyfold (to remove an epoxied fastening you just heat it with a soldering iron for a couple of minutes).

Boatmik

Hi Mik

How much Epoxy should I expect to use ?

Andrew

Howdy,

I would expect that you would use probably a little over 3 litres - so a 6 litre pack would make the most sense - or buy a 3 litre pack and be ready to buy a bit more as you need to.

You will need a kilo approximately of a powder modifier to add to the epoxy to thicken it into a gap filling glue.

Also some TPRDA diluent for where you use the epoxy for coating the ply - it will help spread it out thinly. Don't use the TPRDA in the epoxy where you are gluing or glassing.

I have also added a page to my site about what I did to get a geriatric Sabre in some sort of racing condition.
See http://members.ozemail.com.au/~store...ghyracing.html

Best Regards
Michael

hi Michael,

I've printed off your story (i hope you don't mind) and given it to my son to read, I found it very enlightening.

I picked up the kirri and was stunned on it's properties. The weight/strength are quite surprising.

I have also got the Gaboon so this weekend will be a little busy.

I'll be picking up the poxy on Friday if all goes well.

Regards
Andrew

Howdy -

Where did you get the Kirri from? I have a client building a Eureka Canoe in Melbourne who is trying to get some. He wants to build it light too.

By the way - it might be worthwhile seeing if the class rules or class plans specify the minimum and maximum sizes of any of the solid timber parts. Use the minumum for everything except the width that the gunwales go out from the side of the boat.

The gunwale should be maximum to increase righting moment. In fact - it should be at the maximum from the shrouds to the back of the cockpit (where the crew will be - and minumum everywhere else to save weight.

MIK

Hey Michael,

David at Port Phillip Plantation Shutters (they are importers of Kirri/Paulownia too) would be more than happy to help out.

email : [email protected]

You may also want to have a chat with him about making up kits etc for your canoe as well.

Just let him know Andrew from Hoppers Crossing sent you.

He also showed me photos of a large boat being made from this. Its interesting stuff.

Regards
Andrew

Thanks hugely for the paulownia contact!

It is perfect stuff for lightweight craft - straight grain - good gluing properties, easy to machine.

And epoxy sealing means that this low density wood won't suck up water or rot away.

Thanks again!!!

Michael

No Problem Michael, my Invoice is in the mail :eek:

The piece I am replacing in the cadet is meranti and its lighter than that. I'd love to see one built soley out of Paulownia/Gaboon ply just to see the weight difference.

Yep I can't agree more, it looks like a great wood.

They are also using this stuff in caravans, motor homes etc to keep the weight down. Great for wall panelling as well.

With some scraps try laminating the stuff its light and strong.

Regards
Andrew

Originally Posted by Boatmik

Also some TPRDA diluent for where you use the epoxy for coating the ply - it will help spread it out thinly. Don't use the TPRDA in the epoxy where you are gluing or glassing.

Can anyone tell me where I get the TPRDA in Melbourne ? I Live out west so I don't really want to drive a couple of hrs to pick up this stuff if I can avoid it.

Thanks
Andrew