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PostPosted: Wed Mar 26, 2008 12:22 pm 
I plan to build a Sonnet 14. I also want to build the sponsons myself.

Shall I stick to the lengths in the Yostwerks Kayak Building Manuals?

The background of my question is, that the lengths of the sponsons of Sonnet 14 are 0.6 feet (upper sponson) and 3 feet (lower sponson) shorter than the boats overall length whereas with Sonnet 16 and Sonnet 17.5 the lengths of the sponsons are 1 feet (upper) and 2.5 feet (lower) shorter than the overall length of the boats.

Is this due to the available lengths of commercial sponsons and shall I change it with homemade sponsons?

Thanks for advice,

Markus


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PostPosted: Wed Mar 26, 2008 9:41 pm 
lord high faltbotmeister

Joined: Fri Apr 15, 2005 8:44 am
Posts: 553
Location: Colorado
Quote:
The background of my question is, that the lengths of the sponsons of Sonnet 14
are 0.6 feet (upper sponson) and 3 feet (lower sponson) shorter than the boats overall
length whereas with Sonnet 16 and Sonnet 17.5 the lengths of the sponsons are 1 feet
(upper) and 2.5 feet (lower) shorter than the overall length of the boats.



There is no need for a correlation between the Sonnet 14 , Sonnet 16, or Sonnet 17.5 with respect to upper and lower sponson length.

Quote:
Is this due to the available lengths of commercial sponsons and shall I change it with homemade sponsons?


Folbot sponson lengths are the determining factor. If you make your own sposons,
perhaps a 12' lower sponson would be ok also. You can made the sponsons whatever
length or diameter you wish, though you must be aware that performance can be
affected.

Making your own sponsons from PVC can be a difficilt task unless you are
experienced working with PVC ? ....If not, buying the Urethane sponsons from Folbot
may a better solution. If you have access to a PVC welder, that would make PVC or
urethane sponson construction easier and more reliable than gluing.

Regards,

Tom


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PostPosted: Thu Mar 27, 2008 3:43 am 
Hi Tom,

thanks for your quick answer. My PVC gluing experience is limited to some messenger bags and bike panniers built from PVC tarpaulin. Maybe I underestimated the upcoming challenges ;-).

So I will start with experimenting with homemade sponsons exactly in folbots dimensions. Then I can switch to the commercial product if mine are not reliable.

Do you have any advice not mentioned on your (excellent and helpful) website when building sponsons?

Greetings from sunny northern Germany,

Markus


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PostPosted: Thu Mar 27, 2008 11:13 am 
lord high faltbotmeister

Joined: Fri Apr 15, 2005 8:44 am
Posts: 553
Location: Colorado
Quote:
So I will start with experimenting with homemade sponsons exactly in folbots
dimensions. Then I can switch to the commercial product if mine are not reliable.


That is a good approach. Also consider having the PVC welded . A Sonnet 17.5
builder in Scotland has taken this approach and has achieved excellent results.

Quote:
Do you have any advice not mentioned on your (excellent and helpful) website
when building sponsons?


Commercial sponsons that are the correct size are available for the Sonnet 14 and
Sonnet 16 at a reasonable price from Folbot. I recommend that you purchase them.
For the Sonnet 17.5 and Sonnet Double homebuilt sponsons are required... Welding
is recommended vs gluing.

Blunt sponson ends like Folbot's should come to within about 6" of the aluminum stem
tubes. The length of the upper and lower sponsons will determine the slope of the
stems. Homebuilt tapered sponson ends can get even closer to the stems.

Glued 17' X 4.75" Sonnet Double sponson pics and details are seen below.
Circumference = diameter X 3.14 (pi) .... 4.75" X 3.14"( π) = 14.9".
You must also add for the overlap or lip.

Glued Overlap Seam with PVC elbows ( Right Angle Flange) ...Blunt ends ( non tapered)
Image
Glued Lip Seam with tapered ends
Image

Tom


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PostPosted: Thu Mar 27, 2008 12:30 pm 
Just now I am waiting for the glue (Tarpo-S), primer and accelerator to be delivered. Good time to try welding. I tried welding of PVC tarpauline a couple of years ago for another project and could not make it, because it was too difficult to get the right temperature applied to the PVC. Maybe my heat gun, maybe my technique, I don't know.

Are there any websites, where I can get tipps and tricks?

Cheers,
Markus


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PostPosted: Thu Mar 27, 2008 1:25 pm 
lord high faltbotmeister

Joined: Fri Apr 15, 2005 8:44 am
Posts: 553
Location: Colorado
Quote:
Maybe my heat gun, maybe my technique, I don't know. Are there any websites,
where I can get tipps and tricks?


Markus,

A heat gun may be a possibility when using a special nozzle required to concentrate the
hot air. Below are 2 portable German made PVC welders. The second one uses what
looks more like a conventional heat gun, perhaps with more amps, and the special
nozzle required for PVC welding. I am in the process of getting a portable PVC welder.

http://www.plasticweldingequipment.co.u ... 16235.html

http://www.steinel.de/en/thermo_fuer_he ... elektronic

The attached pics are of welded PVC Sonnet 17.5 sponsons ( 16.5' X 4.25") from
Scotland. The builder glued on the "Boston Valves" and had a commercial shop
do the PVC welding. Cost was about 40 pounds ($80.00US) for welding 4 sponsons
and 2 sleeves, not including the cost of the PVC and valves.

Image
Image

Regards,

Tom


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PostPosted: Thu Mar 27, 2008 4:06 pm 
Tom,
thanks for the infos and pictures. That also looks really professional.

I prefer to try a homemade solution, because I love the feeling of doing things by myself.

I found information at Steinels site and others, that temperatures of about 300 degrees Celsius are needed to weld PVC, depending on the specific material. It must be precisely the right temperature to get good results. So even with an electronic heat gun (and the nozzle to focus the hot air) the speed of welding can make the differnce between good and bad. Sounds like some testing is required.

So as it won't be quick and easy the question is, if welding is really more reliable than glueing? Some time ago I tried to tear glued PVC parts apart and the pvc fibers became visible. So I think it was a pretty good gluing. Can welding be better or is it easier to get it air sealed?

Sorry for asking this chains of questions, but I hope to reduce my risc of failure and save a lot of time for fruitless work.

Cheers,
Markus


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PostPosted: Thu Mar 27, 2008 6:44 pm 
lord high faltbotmeister

Joined: Fri Apr 15, 2005 8:44 am
Posts: 553
Location: Colorado
[/quote]Can welding be better or is it easier to get it air sealed? [/quote]

If done with the right equipmant welding is pretty much foolproof. Gluing can be difficult,
but with practice and experience it should prove adequate. I hesitate to recommend
gluing sponsons for the Sonnets as many things can go wrong on such a critical part
of the boat. Even if you purchase Folbot sponsons , you will still have much homebuilder
work to perform making the Sonnet.

Quote:
Sorry for asking this chains of questions, but I hope to reduce my risc of failure
and save a lot of time for fruitless work.


No amount of work is fruitless as we learn from our failures as well as our
successes. Make some test sponsons and you will have your answer.

Regards,

Tom


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