Shortening a kayak?

With the volume in mind, remember that the 180L modern playboats are
very different boats from what you are looking for. They have a flat
bottom, they are very hard to paddle straight (without experience), and
the ends can dive underwater.

That being said, 360L would be fine (I think). An older whitewater
kayak certainly had less volume and never had any buoyancy issues.

I think I remember reading somewhere about someone doing what Grip has
suggested. He cut a foot or two from the middle of his kayak (or
canoe). I'll try and find it.
 >> Stay informed about: Shortening a kayak? 

Have a look at the pictures on these websites and see if your kayak has
a similar design:

http://www.canoeslalom.co.uk/
http://www.jacksonkayak.com/kayaks06/ricochet.cfm

nick DeleteThis @albion-manufacturing.com wrote:
> Thanks for that, I hadn't thought of cutting them that way!
>
> That might be an easier way of going about it. I'll have another look
> at them with that in mind!
>
> As for kayak type, one has Kiwi (Perception?) and Slalom on it so I'd
> guess it is an old slalom one as you suggested. The other one is
> unmarked.
>
> As you say, I've little to lose by experimenting!
>
> Cheers,
>
> Nick
 >> Stay informed about: Shortening a kayak? 

How about posting pics of them, are they sea kayaks...or perhaps old slalom
racing boats? Either way, if they are being trashed anyway, why not
experiment? From a face value POV, I would keep the ends intact as not to
drastically change the handling characteristics (although any alteration
will do this to some degree) and remove the volume from the middle say just
in front of and just behind the cockpit? Keep it symetrical.



<nick RemoveThis @albion-manufacturing.com> wrote in message
news:1155635418.075005.44910@h48g2000cwc.googlegroups.com...
> Dear All,
>
> I have recently acquired 2 fibreglass kayaks.
>
> Given our lack of storage space, I am considering shortening them.
>
> Has anyone done this before?
>
> I have done some research into glass fibre moulding, and if I was to do
> it, was planning on making a male mould that I would leave wedged into
> the cut ends and lay the fibre over it. My brother has some experience
> of glass fibre moulding and is prepared to advise too.
>
> One is 3900 long, the other 4200 long. The width is around 600mm.
>
> I have calculated the volume of the shorter one as being around 360
> litres.
>
> Surely I can afford to lose some volume given that some modern kayaks
> are as little as 180 litres and I'm not that heavy?
>
> I read a little somewhere about people shortening plastic kayaks, so I
> would have thought this would be more straightforward?
>
> I know it could be quite time consuming and messy but it seems a shame
> not to make use of kayaks that would otherwise have been destined for
> landfill!
>
> I have had some advice from another couple of forums advising that the
> paddling efficiency could be reduced, this is not too much of a problem
> as I will only be covering short distances on a placid local river.
>
> I understand that bouyancy and waterline depth will be affected too.
>
> Any thoughts/advice gratefully received!
>
> Regards,
>
> Nick
>
 >> Stay informed about: Shortening a kayak? 

nick.TakeThisOut@albion-manufacturing.com wrote:

> Given our lack of storage space, I am considering shortening them.

Sell them and buy the kayaks you want. I modify kayaks all the time, but
shortening the hull is just a waste of time and money.

Mike
 >> Stay informed about: Shortening a kayak? 

Thanks for the input!

The kayaks are not too different to the ones on the webpages.

They are old though, perhaps 20 years? They came from a local army
cadet unit, so have probably had a hard life!

I'm not trying to create a playboat, just make something more
manageable for our circumstances. Our local river is an old navigation
and as such is not cleared and has many tight spots (fallen branches
and overhanging trees) where a long kayak could get stuck. Plus I enjoy
breathing new life into old things!

Whatever I do with them, they'll need some TLC. I'll continue to
think about it!

If it's generally believed to be a complete waste of time, I'll fix
them up and get rid. Any more information will be appreciated!

Cheers,

Nick
 >> Stay informed about: Shortening a kayak? 

nick DeleteThis @albion-manufacturing.com wrote:
> Thanks for the input!
>
> The kayaks are not too different to the ones on the webpages.
>
> They are old though, perhaps 20 years? They came from a local army
> cadet unit, so have probably had a hard life!
>
> I'm not trying to create a playboat, just make something more
> manageable for our circumstances. Our local river is an old navigation
> and as such is not cleared and has many tight spots (fallen branches
> and overhanging trees) where a long kayak could get stuck. Plus I enjoy
> breathing new life into old things!
>
> Whatever I do with them, they'll need some TLC. I'll continue to
> think about it!
>
> If it's generally believed to be a complete waste of time, I'll fix
> them up and get rid. Any more information will be appreciated!
>
> Cheers,
>
> Nick

I have to agree with Michael. Shortening a kayak is simply not
practical. Bobbing the stem and stern won't work unless the boats have
long overhangs that could be shortened. Cutting a chunk out of the
center and re-joining the resulting pieces probably won't work since the
boats are not likely to have the same hull shape forward and aft of the
cockpit. It's simply not worth the effort as you'll just end up
destroying the boats. The time and money you waste on this project could
be better spent elsewhere. You would be better off to sell the boats or
give them away and buy what you need.
 >> Stay informed about: Shortening a kayak? 

Michael Daly wrote:
> nick RemoveThis @albion-manufacturing.com wrote:
>
>> Given our lack of storage space, I am considering shortening them.
>
> Sell them and buy the kayaks you want. I modify kayaks all the time,
> but shortening the hull is just a waste of time and money.
>
> Mike
Agreed as well. Assuming you get the right materials to effect the
repairs, there will still potentially be weaker spots and definitely
make a heavier (and probably quite ugly) boat.
Spiff them up, toss a coat of gelgloss on them, and sell them. Then buy
boats you can store and are usable as they were built.

Marsh
 >> Stay informed about: Shortening a kayak? 

Cutting a piece out of the middle of the hull should be no great
challenge. Just be careful to choose the locations of the joined halves
that they match exaclty. Then sand off the inner surface around the cut
and apply a couple of layers of fibreglass soaked in resin through the
cockpit. Boat builders call it a "butt" join. I've used it in plywood
boats. While the boat is in pieces it should be easy to prepare the
inside, move the foot braces, etc.

The challenge would come in enlarging the cockpit. I don't see how you
can cut a piece out of the middle of a kayak without effecting the
cockpit, and they tend to have moulded coamings to keep out the water
and to allow a spray skirt to be tied on. Before cutting I'd want to
figure out what to do about the cockpit.
 >> Stay informed about: Shortening a kayak? 

Wm Watt wrote:
> Cutting a piece out of the middle of the hull should be no great
> challenge. Just be careful to choose the locations of the joined halves
> that they match exaclty.

How many boats have you seen that have the exact same hull profile
forward and aft of the centerline? Not many are designed that way.

> Then sand off the inner surface around the cut
> and apply a couple of layers of fibreglass soaked in resin through the
> cockpit. Boat builders call it a "butt" join. I've used it in plywood
> boats. While the boat is in pieces it should be easy to prepare the
> inside, move the foot braces, etc.

That wouldn't be anywhere near strong enough. To do it right, you need
the inner glass, but you also need to feather the joint back a couple of
inches on the outside, lay in new glass to build the joint up to the
original thickness, then apply new gelcoat.

> The challenge would come in enlarging the cockpit. I don't see how you
> can cut a piece out of the middle of a kayak without effecting the
> cockpit, and they tend to have moulded coamings to keep out the water
> and to allow a spray skirt to be tied on. Before cutting I'd want to
> figure out what to do about the cockpit.

The only feasible thing to do would be to remove the coaming first, then
enlarge the cockpit opening to the proper size after the boat is
shortened. If the cockpit is recessed or the shape of the deck changes
significantly, it will take a LOT of work to reinstall the coaming.

The bottom line is that this project simply isn't practical.
 >> Stay informed about: Shortening a kayak? 

This idea of cutting a Kayak to size seems a bit dumb. Why don't you
just build a bigger storage space? Or if you want to work on a kayak
buy a stitch and glue kit for a smaller Yak. But if you insist on
cutting the kayak. Perhaps put in a 2 sturdy bulkheads about a 1 mm (or
less) apart and cut between them creating two water tight sections that
you can reconnect by butting the bulkheads together and bolting them
firmly in place. You might even want to have 3 reattach-able sections
stern cockpit and bow.
 >> Stay informed about: Shortening a kayak? 

Thanks everyone for your ideas!

I'll let you know what happens!

Regards,

Nick
 >> Stay informed about: Shortening a kayak? 

Brian Nystrom wrote:

> How many boats have you seen that have the exact same hull profile
> forward and aft of the centerline? Not many are designed that way.

"Exact same profile" not required, just at a single point. How many do
you want? These are 20 year old craft. The model names have been posted
so you are welcome to look them up and let us know. Not many are
designed symetrical fore-and-aft today but at one time all canoes and
kayaks were symetrical. The many ways designers use to keep selling
more boats is a topic for another discussion.

Say they are not symetrical. Then the front section can be inserted
into the rear section and locating the cutting lines is not as
critical. Asymetrical would be easier.

>
> That wouldn't be anywhere near strong enough. To do it right, you need
> the inner glass, but you also need to feather the joint back a couple of
> inches on the outside, lay in new glass to build the joint up to the
> original thickness, then apply new gelcoat.

It may or may not be strong enough in a patch or a scarphed panel but
this is a tube. Any tension on one side is compensated by equal tension
on the other. Just sand off the inside surface, position the two
halves, cellotape around the outside to keep the resin from oozing out,
and glasstape the inside. No need to do any fancy finish work to the
outside. One does need, however to cut the hull carefully so the two
pieces fit.
People have reported using single sided taped butt joins on plywood
boats to avoid the problem of finishing the outside surface. Apparently
it does actually work there.


>
> The bottom line is that this project simply isn't practical.

Where does practicallity enter into the hobby of paddling or
boatbuilding?
Giving up a day's pay to drive 200 miles to paddle down a river is
practical?
My own boatbulding is motivated as much by curiosity as practicality.
Can it be done?
Some don't like to spend money but time is no problem.
 >> Stay informed about: Shortening a kayak? 

nick DeleteThis @albion-manufacturing.com wrote:
> Dear All,
>
> I have recently acquired 2 fibreglass kayaks.
>
> Given our lack of storage space, I am considering shortening them.
>
> Has anyone done this before?
>
> I have done some research into glass fibre moulding, and if I was to do
> it, was planning on making a male mould that I would leave wedged into
> the cut ends and lay the fibre over it. My brother has some experience
> of glass fibre moulding and is prepared to advise too.
>
> One is 3900 long, the other 4200 long. The width is around 600mm.
>
> I have calculated the volume of the shorter one as being around 360
> litres.
>
> Surely I can afford to lose some volume given that some modern kayaks
> are as little as 180 litres and I'm not that heavy?
>
> I read a little somewhere about people shortening plastic kayaks, so I
> would have thought this would be more straightforward?
>
> I know it could be quite time consuming and messy but it seems a shame
> not to make use of kayaks that would otherwise have been destined for
> landfill!
>
> I have had some advice from another couple of forums advising that the
> paddling efficiency could be reduced, this is not too much of a problem
> as I will only be covering short distances on a placid local river.
>
> I understand that bouyancy and waterline depth will be affected too.
>
> Any thoughts/advice gratefully received!
>
> Regards,
>
> Nick

I may have missed it, but by how much are you needing to shorten these
boats?

>From what you have written, you are looking to end up with something to
go swamping in, and they don't need to be particularly pretty. Also
does not sound like you are doing any wild water, just need something
highly manueverable to negotiate the backwater?

You might just clip the ends back to the desired length, and then glass
over the opening to be water proof. That way, the load handling central
structure will not be compromised, as well as the rocker that is needed
to turn easily. Also you will not have to mess with the combing if you
plan to use a spray skirt.

The sharp pointy ends are not needed really as demostrated in the newer
generation of playboats and creekers. You are not looking to achive
great speed characteristics, and depending on how good you are at the
glass work, will tell how the finished product will be.

You could always mount some sort of maiden form on the bow to scare off
the swamp gods, or maybe attract a mermaid! HYY
 >> Stay informed about: Shortening a kayak?