Three-part Searacer – Rune Eurenius

Friday, July 5, 2013 (launching, Sea Racer), 15 comments

A very interesting 3-part Sea Racer from Rune Eurenius!

"Posting pictures from the maiden voyage of my Sea Racer. Paddling the Sea Racer gives me associations of driving a sports car. The transition from my Hunter was easy, despite the relative low initial stability. I am not able to comment on the speed performance as I am in a relatively poor physical shape at the moment.

The integral rudder presented earlier ( http://www.utsidan.se/albums/view.htm?ID=7763 ) works really good, even at low speed. A well constructed carbon fiber cockpit rim from Petrus Kajak fitted almost perfectly with one centimeter to spare at the widest point.

The build was relatively complicated due to the 3-piece construction. There was no other option for me as I have no suitable space for a conventional build (or storage for that matter)

The kayak was constructed in my 67 sq.yd. apartment during 10 months. It actually worked out very well. Problems with noise and dust was eliminated with a fantastic Festool RO125 multi mode sander, connected to my vacuum cleaner.

There are virtually no play in the joints and the kayak feels solid despite the 3-piece construction. The joints are held together with countersunk M8 bolts, treaded in corresponding dome nuts. These are molded into 1 1/2" plywood beams with West Systems epoxy. 5/8" holes was drilled through the hull to accommodate glass fiber reinforcements for the bolts. See photo.

Regards, Rune"

A short video clip from the launching: vimeo.com/69502755 (an integral rudder as an auxiliary engine ;-)

Comments

1 Pelle Eriksson
7/4/2013 9:51 PM

Smart lösning med delningen av kajaken när du har ont om utrymme att bygga (och förvara?) på! Det där blev jag riktigt imponerad av, -snyggt!

2 Rick Hayhoe
7/4/2013 11:10 PM

Rune,

Undaunted by limited apartment space, you seem to have put some very fine craftsmanship into the project. Congratulations!

Your solution to limited transport and storage space by dividing the kayak into three parts is intriguing. Here in Japan, the land of overcrowding, that could be a boon to kayakers. Please let us know how it works out over a longer time.

By the way, a designer in New Zwaland of sailing outrigger canoes and proas, Gary Dierking, has done the same thing, making one of his longer canoes, his Wa'apa, divisible into three parts. An interesting aspect of his solution is that he has the plywood bulkhead panels face each other on the outside, with the timber framing inside each compartment, so the timber is not exposed to water. He saturates the exposed plywood with epoxy. He puts a neoprene washer round each bolt before he joins the sections together on the beach. That prevents water seepage through the bolt holes.

I wish you much success with your new kayak.

Rick

3 Rune E
7/5/2013 10:05 AM

Thank you both for the kind comments :-)

Rick, I found quite a lot of info about Gary Dierking on the net. Even a Wa´apa video at YouTube. Interesting stuff.

4 Rick Hayhoe
7/5/2013 11:26 AM

Typographical error. Gary Dierking is in New Zealand.

5 Björn Thomasson
7/5/2013 6:54 PM

Rick, that is the usual way (as seen here), but Runes method has three advantages (if I understand it correctly from the pics): 1. the timber "keying" the parts (lego-block-style), and thus releaving the bolts of the any sheering forces, 2. the bolts are accessible from the outside – no crawling into small compartments to reach bolts or nuts (the Sea Racer is a low volume kayak) and 3. no exposed bolts that can get damaged during transport and storing.

Have I got it right, Rune?

6 Rune E
7/5/2013 7:53 PM

That is correct Björn. And Rick, yes, I will let you all know if the joints fail in any way.

For the piece of mind, I cover the lower bolts with duct tape to prevent them to come off. They all seem to remain tight so far

7 Rick Hayhoe
7/6/2013 1:42 PM

Ah! Maybe I understand. Minutely scrutinizing Rune's photo of the kayak in the back of his car while taking into account your description, Björn, if I see aright, there are five bolts fastening the fore end of the cockpit section to the stem section of the boat, and four or five bolts for joining the after end, each bolt screwed in from the outside of the hull skin. The two ends we cannot see in that photo must, therefore, have projections from their bulkheads that fit snugly into the recesses in the bulkheads we can see. Is that it?

Should I read that M8 bolt as being 8mm ø?

8 Rune E
7/7/2013 5:51 PM

Rick, You´re right in your assumptions. Here´s an illustrative image http://www.utsidan.se/albums/viewpic.htm?ID=66537

All wood surfaces are sealed with fiberglass/epoxy

9 Rick Hayhoe
7/8/2013 5:59 AM

Thank you, Rune. The photos very well illustrate it.

I am further amazed that you actually built the kayak in the three parts and still managed to get such a fair hullform. I had assumed that you must have cut it into the three parts with doubled bulkheads installed, after gluing up the planking.

Congratulations on a remarkable job: for how well you solved your space and attachment problems, how well the boat came out, and especially for your tenacity.

10 Dan Caouette
7/8/2013 1:26 PM

Very ingenious, Rune! I'm currently about 80% of the way into a 5-piece sectional Black Pearl build. I'm using the "usual" method of double bulkheads and through bolts. Your method seems like it should be more robust.

11 Dan Caouette
7/8/2013 1:27 PM

Forgot: With the exterior bolts it'll also be much easier to put together and take apart on the beach. Well done.

12 Rune E
5/10/2019 10:02 AM

Här finns ett bildspel med kommentarer på min i vinter itusågade och hopskruvade Hunter.

Samma konstruktionsidé:

https://www.utsidan.se/albums/slideshow.htm?album=9252

13 Rune E
5/10/2019 10:23 AM

"Itresågade" blir det ju. Men då låter man ju som en stockholmare..

14 Petter
9/5/2020 2:27 PM

Thanks for sharing this Rune! Its very inspirational, and I'm hoping I can pull it off. To alleviate the concern of bolts coming undone I'm thinking stacking some regular nuts followed by a Nyloc nut and a dome nut instead of the long nut shown in the photo album.

I just hope I don't chicken out when it comes time to take the saw to the hull..

15 Rune E
9/9/2020 7:44 AM

Hi Petter!

I have paddled a lot in my three piece Hunter the past two years and the bolts have not shown any tendency to come loose. I guess this can be attributed to the large friction area of the countersunk heads.

Captive nuts are of course a simple alternative to my solution with extension nuts.

https://www.thomassondesign.com/en/bygga/download/take-apart-kayak

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