Tim thats the one i have been using for most of my info

Bill wrote:Thats what I mean. I'd have thought whisky would be the preferred tipple for problem solving.

Bill

If I'd cracked the Scotch I'd never have got back tothe boat.

After a extra hours at the end of the day I completed the three piece and its a goer
A few tricky bits but with a bit of faith kept the ball rolling

its surprisingly much stronger than I thought and the cut lines up perfectly

I'll have to work out the best way to stop water seeping in through the bolt holes any ideas?

Just have to finish off building it now

Looks good!
For sealing I would use a thick rubber or even better , urethane washers or bushes like these skate board bushes. They will under compression ,bulge inward to seal the bolt and also keep the nut under tension. The great thing about the skate ones is they will look a bit more pro if your showing a client and they come in different duro's.

Dont know if it woold upset the join, what about a beed of silicon around the edje on one face and ruber washers that are a realy tight fit around the bolts, you mat wont to cut sume ruber tubing to slide onto the bolt ends after the thing is asembald to protect gear and feet ect...

I like that Tim especially as it gives my young fella a chance to drool over the skateboards at the local shop (he just won an under 7 skateboard comp in the holidays and is a mad boarder) --how small do they squash and I imagine they are used on the outside of the join?

Hi Mick yeah I could use a bead around the outer but it gets a bit messy cleaning off the old stuff each time you would want to rejoin again

Yes mate , on the outside of the joint inside the kayak on either side. So 1 under the bolt head and washer and one under the nut and washer with only the boat in between. I don't think it would need anything in between . maybe a thin rubber washer but only to stop chafing.
Most street skaters use bushes as hard as you can get but longboarders like me like it soft
I would buy some of the Khiro double barrels in 85a and see what you think. Bite on them and you will get an idea how they would go. maybe even the 79a.

nice I'll use them cheers

Ahoy gages,

Good on you with your 'export' project, hope it will take off .
Make sure that you label it as a 'prototype' (especially if it goes to North America)...

Personally, I would prefer the use of a X cross instead of the two bumps (for the self aligning of the bulkheads) and 4 screws insted of 2 shown on your pics.
The water sealing is important, but first, you must decide from where (the hatch or the cockpit) the tightening will take place.
It would also make sense to modify the screw heads and then secure them (glass them to the bulkhead) permanently in order to prevent it from spinning. Create the 'rubber' washers from excess EVA seat material (3mm thick and only between the joining sections). Once the sections are tightened, the EVA washers should 'seal by expansion'.

I would also prefer to use S/S flat bars rather then the pictured round washers,for more even distribution of pressure. If not, then make the bulkhead a bit thicker. Use oversized S/S wing nuts (including spring washers) on the end of the screws.
I know that you are on a tight budget, but at least run masking tape along all the section edge lines and spread a thin bad of Sikaflex, flaten it to 2mm using a flat knife dumped in turps for silky smooth finish.
What you have just created is 20 mm wide strip on every section.
The combined 4mm will work as a compression/expansion gasket between the sections.
Nothing about water sealing but more about the different stress factors along the joined sections.
Later on, you could order 3mm thick EVA sheets and cover the entire section rather then mess with the Sikaflex.

The last and most important bit: after you bank your first million dollar order, don't forget about the Hybrid "Unlimited" project!

thanks Andre

Firstly the two bolts were there for initial alignment to see how they lined up (100%) and even though I thought of glassing them in it would make for a terrible outcome if by chance a bolt was threaded and that was why I have not gone with this after thinking this would be the best situation,it would also leave exposed bolts hanging out one side permanently, --I need to work this one out a bit more

The bulkheads are amazingly strong and if you had a look and feel you would be impressed ,I know know how than can fly airplanes made out of composites

I will be using the seat material as suggested but have ordered some of the gear Tim recommended,cutting edge and excellent material--Thanks Tim

The three piece has been built so I can easily get it into a plane so I can show prospective customers overseas what a boat looks and feels like

Thanks Andre its always good to have a few ideas rather than the one

it was such a good project I have deceide to BLOG about it and other things composite read about it here
http://nadgee.blogspot.com/

Nice ideas Andre.
I agree about the cross and the wing nuts to encourage people not to over tighten but as a consumer I hate the idea of captive bolts that I can't replace. I know its probably the easiest way to bring the 2 halves together but .......... Also using EVA to seal the joint, correct me if i'm wrong but doesn't EVA have not enough memory? That is , it won't expand back to its original dimension after a long time compressed. A trip of a week may render the EVA useless. I was thinking about 3M Body Schutz sprayed on between the panels also but it may be a little heavy. You would need to test that. Once again I like the idea of Urethane . Not in the form I was talking about before , that was just as a quick fix but instead to make a full size gasket. A sheet of glass leveled would make a good surface to pour some urethane resin onto. Then you just need to cut to shape. Unless of course you can buy it in sheets?

...designs based on bolts and screws are never the most elegant (with or without the washers!) but should be OK for a prototype.
Later on the skeg or rudder cables will all fit in as well...
Sharing our love of the sport and working as a 'team forum' makes sense.
Arguing about portable electric pumps doesn't

Coming from a completely different industry, if I was faced with the sealing issue I would suggest sealing the shaft, not the clamping faces.

For example, a viton o-ring or better still an angled face double lip spring reinforced shaft seal recessed into each half. This will absolutely seal each half and allow you to have rigid clamping faces to discourage movement and loosening of clamping bolts through vibration and fatigue.

Then again, I have no experience with kayaking, let alone keping mating sections together - and whether a little give in the clamping faces is desirable....so I could be talking out of my behind.

they may not be the most elegant but they would be the strongest compared to clips which leave no holes but are weaker when it comes to distortion from waves etc
There is a lot of tried and tested methods out there and it seems from my own investigation that the nut and bolt work fine as its easy to over engineer and the simplest to replace if something goes wrong


gcouyant do you have any photos of this application as I see merit in it? and there is nothing wrong with your suggestion

Rudder or skeg its an easy fit already as this one will be a Rudder version

gages wrote:gcouyant do you have any photos of this application as I see merit in it?

Lawrence the shaft seals come in so many shapes and sizes it's scary. Complete rubber coated with stainless tension spring such as this below:



or metal frame (available in brass) for interference fit into the recess:



The section profile is like this:



With a smear of waterproof grease (quality wax based like Belray waterproof grease) the seals should do the job well.

The recess for the seal is a matter of finding the matching size cutter (seal outer diameter) with the right size arbour (matching the holes already drilled) to ensure that you drill centrally and go as deep as is required by the width of the seal.

Here's an example of one of these seals installed:



Hope this helps.
George

Thanks George -its definitely the goods -do you make them or where do I source them as little old Bega is a bit dry on quality components

gages wrote:Thanks George -its definitely the goods -do you make them or where do I source them as little old Bega is a bit dry on quality components

I think that you'd be surprised at what is available in Bega. The local mechanics and most farm sheds will most probably have boxes of used, but too good to throw out seals.

A couple of catalogues of lip seals that you should be able to order from an industrial supply store.

http://www.fluidseals.com.au/files/catalogues/Fluid%20Seals%20and%20Packings%20-%20Hydraulic%20and%20Pneumatic%20Seals%20Catalogue.pdf

and

http://www.timken.com/en-us/products/seals/industrial/products/Documents/7707.pdf

Do you have a box of assorted o-rings? That is another option that may be quicker, field servicable if you use standard sizes and almost as effective (again with a smear of grease). The only hassle will be holding the o-ring captive. Perhaps a large stainless washer that is drilled & countersunk for a couple of retaining screws over the o-ring and a flush outer face - something like this:

My 3 piece Nordkapp (pictured earlier in this thread), uses only simple neoprene washers.

don't over engineer a bolt conection.....mine doesn't leak. The washers mush and seal.there is a threaded insert built into the bulkhead, so that the bolt is tightened into the one bulkhead...it can be replaced if needed, not glassed in.

Best wishes
Roy

Fadedred wrote:don't over engineer a bolt conection.....mine doesn't leak.

You're probably right Roy and this may indeed be the norm in the Kayak world. It's just considered to be good engineering practice to seal the shaft and not the clamping suface. As for over engineering, it's hard to tell when to stop - not unlike dancing on the table with a belly full of beer.

Cheers
George

Come on Lawrence you must be finished by now..........where are the pictures?