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PostPosted: Fri Aug 21, 2009 1:29 am 
Hi there! I am new in the forum, and in the world of folding kayaks in general. I have constructed a Sea Tour 17 a few months ago and have had a lot of fun paddling it in day long trips.But how about the durability of the boat in really difficult conditions, tricky landings and multy day expeditions?has anyone tried them? the things that seem a little vulnerable to me would be the PVC skin and maybe the skrews that connect the aluminium tubes to the bow and stern. Has anyone ever had any failures and where? and finally how many years will the boat actually last?


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PostPosted: Sun Aug 23, 2009 2:08 pm 
Quote:
I have constructed a Sea Tour 17 a few months ago and have had a lot of fun paddling it in day long trips. But how about the
durability of the boat in really difficult conditions, tricky landings and multy day expeditions?has anyone tried them? the things that seem a
little vulnerable to me would be the PVC skin and maybe the skrews that connect the aluminium tubes to the bow and stern. Has anyone ever
had any failures and where? and finally how many years will the boat actually last?


I know of at least two Sea Tour 17 folder's that easily survived 500km trips. Many are used for coastal paddling, so "seaworthy" should apply here.

Since you built the Sea Tour 17 yourself, you are now an expert at repairing and replacing any parts that might fail. In light of that, I'm
rather surprised that you would question the durability of the boat as you know exactly how to easily replace the stem screws if needed,
patch or replace the hull if required, and replace stringer sections if bent. In other words, your Sea Tour 17 will last as long as you want it to.

My oldest aluminum / HDPE homebuilt folder is over 10 years old, and it's still going strong. It's got a few patches, but the machine screws
holding the stringers at the bow and stern have never failed. I've had HDPE stem plates split, and I replaced them, but on my newer boats,
I no longer use HDPE stem plates, but rather simple aluminum tabs... easier to make and maintain. I've never had any problems with HDPE
cross sections.

If you are making hard landings, add rub strips to reinforce the keel and chines. Always carry a small repair kit stocked with PVC ,
vinyl cement, machine screws, a roll of duct tape, and anything else you deem necessary.

These frames and skins are simple in design, and easy to maintain.... but you should already know that :D
The Sonnet inflatable / folders have no stringer to stem connections, and no HDPE cross sections, so they are simpler yet.
Sponsons can fail over time, so I always carry a spare sponson or two.

Below is a non folding wood frame Sea Tour 17EXP with a sewn nylon / brushed urethane skin in small waves... I assume it
survived the landing :shock: I'd be more concerned about a wood frame non folding SOF like this than an aluminum
frame / PVC skinned folder. If you can take it apart, you can usually repair the frame or skin on site.

Hope this helps, Tom

Image


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PostPosted: Mon Aug 24, 2009 12:09 pm 
Thanks a lot Tom! i guess my concerns where more psychological than based on logic, before starting to use the boat in real hard conditions in the Aegean! Thanks for the beautifull plans and instructions in your site


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PostPosted: Thu Sep 10, 2009 1:56 pm 
A folding kayak isn't an ABS canoe, by any means. I put quite a few holes in the skin of my Sea Tour 17R the first couple of times out, the worst was landing on a cobble beach with 0.5 metre dumping waves. The boat (and I) were pounded three times HARD before I managed to fall out. I finished the trip bailing the cockpit about every hour. Somewhere in there I also manage to shear the three rivets holding the stem piece on, but never noticed until I dismantled the boat for winter.

So I accepted the additional weight and doubled the skin along the keel and both chines. I'm planning on smoothing the edges of the HDPE frames to minimize cuts on easy landings.

There are few if any critical parts whose failure will make you swim. The skin damage is nearly always against a frame part so the holes are small. The real secret is to get your feet wet when launching or landing and your kayak will thank you.


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PostPosted: Thu Sep 10, 2009 2:45 pm 
SeanRichens wrote:
...
So I accepted the additional weight and doubled the skin along the keel and both chines. I'm planning on smoothing the edges of the HDPE frames to minimize cuts on easy landings.

There are few if any critical parts whose failure will make you swim. The skin damage is nearly always against a frame part so the holes are small. The real secret is to get your feet wet when launching or landing and your kayak will thank you.

All good points. In the absence of home-builder skills (and space, too), I'm satisfying my urge to "perfect" things (don't know if this is something creative or a sick obsession ;-) ), by implementing these measures on commercial models. I've added protection strips to under deck (over HDPE ribs). Feathercraft have protection strips outside in all the right places and inside along the keelsen, - so I didn't have to do this. I also smoothed both inside and outside edges of HDPE ribs (outside - where they contacted the deck, and inside - to eliminate occasional scratches on my skin). FC HDPE ribs are carved so that they don't have much contact with hull - only with deck; hull fabric is stretched against frame long members.

Getting in and out of the boat in a few inches of water has become a sacred ritual to me, not only with folders, but with composite hardshells too (composites are not easy to damage, but when it's already 12 years old, costly and messy gel coat repairs become sooner and sooner with every careless ride over shore pebbles).


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PostPosted: Thu Sep 10, 2009 7:04 pm 
Softer is better.

I'm betting that the Sonnet's lack of hard parts to bash against soft parts, and it's likely greater overall flexibility, will be more bash-friendly. This is speculation as I have never paddled one.

Pakboats canoes use a thin closed cell foam pad on bottom between hull and frame, specifically in order to avoid this type of damage. Seems like a good idea that could be adapted to many skin on frame foldables.

Needlessly grinding any boat onto a beach is a no-no.


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PostPosted: Sat Sep 12, 2009 2:32 pm 
[quote]Saleroso wrote... I'm betting that the Sonnet's lack of hard parts to bash against soft parts, and it's likely greater overall flexibility, will be more bash-friendly. This is speculation as I have never paddled one.

You are correct sir 8)

The Sonnet's normally have an 18oz vinyl hull, and the sponson sleeves are 10oz vinyl. This protects the sponsons quite well, and as you have said, the lack of hard contact points at the chines ( sponsons) means less chance for damage. I might add that the Sonnet will still float quite well even with both bottom or both top sponsons deflated and for that matter with a left top and right bottom deflated. I tested this extensively before offsering plans for the boat. Plus, if swamped, 4 sponsons make it float very high, and easy to control, even in rough water. In fact , a fully swamped Sonnet 16 is easy to roll.

I'm currently building a new Sonnet "Combi" using 6 Folbot 15ft sponsons. This hull is deeper ( 11") and the boat is short at 15.5' X 26" beam. Designed load is over 500 lbs. Below are a couple pics of the skinning frame. The only part of this framework that will be a part of the finished boat is the 1" keel tapering to 3/4" at the stems. Weight will be about 30 - 35 lbs and assembly easily under 15 minutes.

A friend and I are motorcycle touring New Zealand's South Island next Spring and this boat will double ( pun intended) as both a double and single with it's three coaming deck. Fiordland here we come. :shock:

If there is any interest shown in this project, I will post updates. Cheers, Tom

Sonnet "Combi" skinning frame and Sonnet 16
Image

The vertical looking stems have a 6" rounded entry.
Image

"Kanu" is the open deck canoe version...."Combi" is the kayak version.... Same hull design. Unlike the drawing all sponsons are 15' and the keel is 1" tubing.
Image


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PostPosted: Mon Sep 14, 2009 9:46 am 
Quote:
I'm currently building a new Sonnet "Combi" using 6 Folbot 15ft sponsons. This hull is deeper ( 11") and the boat is short at 15.5' X 26" beam. Designed load is over 500 lbs. Below are a couple pics of the skinning frame. The only part of this framework that will be a part of the finished boat is the 1" keel tapering to 3/4" at the stems. Weight will be about 30 - 35 lbs and assembly easily under 15 minutes.

If there is any interest shown in this project, I will post updates.


YES, there is great interest in this design, so please do keep us up to date.

What is your reasoning on the 3 equal length sponsons, making for blunt bow and stern? (BTW, my blunt stern Innova Helios is a great surfer and handles well in following seas).

Will you be using 18 oz hull material for this super cruiser, or something heavier?

You are aware that the 15' Folbot sponsons are no longer available, so please take into account that the rest of us will have to use 16 footers.

In my materials search I have been directed a number of times to TriVantage, a distributor of covering fabrics like vinyl coated polyester with distribution centers all over the country. http://www.trivantage.com/about/distro.html Their website requires a bit of perseverance to get all the info you want, but worth the effort. Looks like they have a great selection of materials. Here's one page to look at with an interesting product. http://www.trivantage.com/allweather/fa ... eytxn.html If there is one close to you, seems like it would be worth the effort to look at what they have.

Please keep us up to date with developments, your thoughts, changing specs, possible design variations. I have been working towards a Sonnet, locating materials, etc, and would like to see where this one goes before further commitment.

And again, many thanks for sharing your work with the rest of us.


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PostPosted: Mon Sep 14, 2009 4:31 pm 
Quote:
What is your reasoning on the 3 equal length sponsons, making for blunt bow and stern?


It's not blunt, just vertical :D I did it partly for displacement, partly for waterline, and partly because I just felt like doing it this way. Plus, it's also going to be an open deck canoe, so the stems look the part. As I mentioned earlier, the stems are rounded for the first 6 inches due to my electricians tube bender, and that means it's not vertical in the water for the most part as the waterline is less than 6 inches, and induced rocker will likely raise the tips a bit more.

Quote:
Will you be using 18 oz hull material for this super cruiser, or something heavier?


18oz PVC hull, 10 oz PVC deck, or possibly a coated nylon deck. Sponson sleeves will be sewn ripstop nylon vs the glued pvc sleeves I've used in the past. Lighter weight and smaller fold size are the reason. Downside is the need to find someone to sew... Rita volunteered to do the sewing on her Pfaff and is nearly finished.

Quote:
You are aware that the 15' Folbot sponsons are no longer available, so please take into account that the rest of us will have to use 16 footers.


Yes, and the drawing show both lengths. The skinning frame is easily stretched 6" at both ends using the existing stations ( cross sections). I already have several 15 footers, so why spend more money for 16 footers.... though I'd prefer the longer ones.

Tom


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PostPosted: Tue Sep 15, 2009 6:57 am 
Quote:
it's also going to be an open deck canoe


I understood 3 cockpit deck, so something like the removable Pakboats decks, with support structure built into the deck?

Quote:
Sponson sleeves will be sewn ripstop


How will you attach nylon sleeves to hull?

More and more interesting.


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PostPosted: Tue Sep 15, 2009 7:05 am 
As it appears that the Sonnets count on the induced rocker of center paddler to optimize their shape, it also appears that having two paddlers, one at each end, might induce a negative rocker. What are your thoughts on this? I seem to remember seeing on your website that an open canoe was your first Sonnet prototype...

Should we be starting another thread for this?


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PostPosted: Tue Sep 15, 2009 9:18 am 
Quote:
As it appears that the Sonnets count on the induced rocker of center paddler to optimize their shape, it also appears that having two paddlers, one at each end, might induce a negative rocker. What are your thoughts on this? I seem to remember seeing on your website that an open canoe was your first Sonnet prototype...?


They aren't at each end in the kayak.... likely 5ft - 6ft apart... and no negative rocker. More likely very little rocker change in the double kayak based on optimum paddler placement. These boats will carry lots of volume near the stems, and that will help. I'd like to have 6ft spacing between paddlers, but what you want and what you get are often at odds.

The 3 hole kayak deck is not removable... I considered a washboard coaming with separate 1 and 2 hole spray deck's, but I find washboard coaming's with large spaydecks difficult to keep watertight, especially on a farly low riding kayak like a Sonnet. I assume a removable deck like you mention will be even more so.... for me anyway.

The canoe will be a separate boat, and it could have a stiffer ladder ( two tube) keel. I'll determine that when, and if, the time comes. The canoe will be built later, though we'll test the kayak before the deck is attached to determine paddler placement. The kayak build will determine in large part what changes are needed for a canoe version. A deck vs no deck is not a factor as the deck is non structural ( no tubes) in the Sonnet's. All in due time.

No new thread at this time... perhaps later when I have more pics / info to add... in a week or so.

The nylon sleeves will have 2ea X 1" PVC ( 10oz) sewn strips running 15ft lengthwise along the base. These strips will be sewn at the 3/4" separation between the individual sleeves... between sleeve 1 and 2 and between 2 and 3. The sleeves will be glued to the sides of the hull, same as the Sonnet 16.

You might question why glueing them in place is necessay.... It's because the side stringers are free standing, and that necessitates anchoring the sponsons in place so that the tubes can be correctly inserted before full inflation of the sponsons. The 1" PVC strips are glued at the exact location of the stringers. I suppose the sponsons could be velcroed in place, but that would mean added bulk, more work, and more cost.... plus I really don't like velcro.

This time around however, the hull skin will first be placed wrong-side out on the skinning frame, and the sleeves attached before the skin is turned right-side out for final trimming and gluing up of the stems.... In theory anyway. The sponson sleeves are, in my opinion, the most complex part of the build. Thankfully, I'm not doing the 240 ft of sewing. ( 30 ft x 8 sewn seams)

That's enough thinking for today. It's time for a ride in the twisties to clear my head..... :D Cheers, Tom

Image


Last edited by Yostwerks on Tue Sep 15, 2009 10:10 am, edited 1 time in total.

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PostPosted: Tue Sep 15, 2009 10:05 am 
Quote:
No new thread at this time... perhaps later when I have more pics / info to add... in a week or so. After building 40 or so kayaks over the years, I don't pre-think a lot anymore. I just design , build , and solve problems as they arise... and I assure you, they will arise .


Thanks for your patience with my questions. Glad to hear that your time frame for this project is NOW. I'll try to contain myself...


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