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The GOSSIP

Number 143 / April 2003

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Published by the Open Canoe Sailing Group

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overlaps. Prepare mating surfaces by roughening the surfaces with abrasive paper. Along the length of the tube one inch from the edge apply a strip of masking tape. Do the same along the other edge on the opposite side (see fig 1). This is done to get a clean glue line. When the adhesive is applied to the mating surfaces it's bound to spill onto the masking tape. When the glue is tacky, simply remove the tapes, which leave two neat 1" lines of adhesive. To seal the ends of the tubes the inner surfaces are simply glued together to form a 2" wide flat strip. These are made wide to allow for fitting brass eyelets at each end. Use tape again

to get clean glue lines but fit it 2" from the end having suitably abraded the surfaces. (Note: when bonding these together you have to consider the overlap joint along the length which has to be done first to make the tube.) It sounds tricky but it's fairly obvious when you start to make them. For simplicity when making the end seals make sure the overlap joint along the length is towards the centre of the end seal but not where the eyelet goes (see fig 2).

Bonding with the P.T.A. can be done by a hot or cold method. I find hot is easier.

Cold bonding: apply adhesive to both surfaces, when tacky press the surfaces together then lightly hammer, or I use a small decorators wooden roller to apply pressure. Potential snag!! If you position incorrectly you are stuck so to speak, you cannot reposition.

Hot bonding: Apply adhesive to both surfaces, allow to dry thoroughly. Position the material in place, it won't stick yet. Then apply heat to re-activate the adhesive. I've used either a hot air gun or a steam iron. Remember it takes time for the heat to penetrate the fabric to get to the glue. Then apply pressure to the joint by hammering or rolling. It is recommended not to exceed 80 C (at the glue joint) which I have not found as yet to be too critical. If you adjust the iron so that it just starts to produce steam and back off a little you may be at 80 degrees.

For inflation nozzles I have used various types including those from old airbeds or dinghies. I now have a small supply of new plastic ones of which I could spare the odd one or two. These need careful preparation as the mating surfaces are small but so far have been reliable. Fit them with the flange on the inside of the tube before gluing it all together and as extra security stick a backing washer of the material on the back of the flange also as in Fig 3.

There is a more simple method of construction for sponsons, end bags and internal bags which is not quite as strong or professional looking but is less prone to leak due to the lack of overlap joints. To make them fold appropriately sized material over along its length. Make seams along the 3 open edges using tape inside as before, having of course fitted the inflation nozzle. Glue the inside edges together resulting in them looking like Ravioli or pillowcases. As bags are very cheap to make compared to commercial units they are worth a try as a first attempt. Before starting I recommend experimenting with test pieces with both hot and cold bonding and testing them to destruction, you'll get a feel for how strong the bonds are. Remember it takes 12 hours of so to achieve full strength.

Note!! There are no guarantees with my methods, if you use them it's entirely at your own risk. The British Standards Institution is not using my Quality Control as the Gold Standard. But nevertheless I've been using some of my bags for over 6 years without failures. (Yet!) If you make your own bags, test them mercilessly to give them more abuse than they will find in a boat! It's easier than improving your swimming.

I'm hoping to continue with methods of attaching sponsors to canoes but contact me now if you need more information or have any suggestions.

 

More Ways To Kill The Cat (JohnB)

The recent discussions in the GOSSIP about jib sails were interesting in more ways than one. While there can be little doubt that the views put forward by the respective authors are quite correct, namely that (a) a tight forestay will bend the mast forward and distort the main and (b) there is not enough beam to allow the sheet to be properly positioned, they do reflect our penchant for seeing the obstacles to problems rather than looking for solutions.

As far back as the 1930's, Uffa Fox overcame the rule of having to have two masts and set his forward mast in the eyes of the boat at something like 45 degrees with a 'jib' sail on it, it was not fastened to the 'mizzen' mast. Where there is a will there is often a way and this way was good enough to beat the best of the Americans.

We might also consider using a luff spar, say 1 inch OD, which would be fastened both top and bottom; this would be very stiff and would still allow a pretty clean airflow over the sail.

There seems to be little doubt today that using a jib will improve the airflow of the whole rig; a higher aspect ratio main will reduce the drag. An increase in efficiency without an increase in overturning moment. It's got to be worth trying.

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