DIY Spearo Sit-On Canoe

[Jonny250]

OK this comes out of my recent ponderings over which way to go for my float and carrying the various bit's of kit.
I currently use a standard inflatable orange float with clips, flag, strobe light, stringer and limited adjustment of the float line. However as we have been debating the options on floats (over in the Guernsey 08 thread)- and what would be good to include on a 'new' one, I came to the conclusion that [for me] the current setup is good. However looking forward to future trips, I figure it could be good to get out further from the shore, quickly... and hence a canoe seems logical. I already have a couple of plastic sit-on canoes and they are toooo heavy! So my idea is to make a mould and then make a sit-on.
I have so far only just started working this out, but would be keen to get other peoples advice and ideas; I've read through the (long and interesting) thread on sit-on canoes elsewhere on DB, however this is more about "what if I could build features into it" rather than mods/kit for existing canoes.
A couple of essentials: must be lightweight - one-handed carry or on a shoulder like a waveski is carried. Weight budget approx 8kg.
Fishbox in the bow, see picture below.
Stable, suitable for novice paddler.
I'd be interested to know from people with sit-on's what they would suggest for a new spearo sit-on.
I've included a low transom to make it easier to pull yourself on - rather than over the side. Immersed volume as shown is 100 Litres.
Here's some pictures of where I've got to so far...

 

[Pav]

Construction : If home made its GRP from a mould or Shaped foam which is then covered by GRP (like surfboards and custom surf skis are made). If its a 1 off I would expect the process of shaping the foam and then glassing would be best (if I can help further ask as I shape and glass surfboards). This will produce a light weight ski. You can lay the glass up stronger in areas where you think you need it. Repairs are easy alike surfboards. The only issue is where you would get a blank the size you need. I am pretty sure you can get large foam blanks which are destined for windsurf boards. You may have to put in your own stringer?

or... Ply construction! , I have seen paddleboards made this way.

for innovative ideas look at the surfskis (sitons) from south africa.

Keep us informed with your ideas and construction.

 

[Magpie]

Erm, Jonny nice design but to me there's one standout flaw, isn't it going to be tippy as hell with you perched up that high? If you make it wider to compensate then it'll be a dog to paddle. With someone kneeling on it like that the centre of gravity is going to be very high and the slightest swell will mean you're swimming long before you get to your dive spot!


Sitons are always a tradeoff between speed and stablity, generally the quicker narrow sitons are far more unstable than the wider, slower ones and you pick what best suits your purpose.

If you're touring you pick something narrow so you can get about with the minimum effort, if you're fishing you want something a bit more stable to fish from and have a higher load carrying capacity for all your gear.

 

[glowworm]

Not knowing much about these things but could you not put a fin or blade underneath to make it more stable in the water like a windsurf board?

I like the design and wouldn't mind one myself.

 

[Jonny250]

Thanks for the comments and thoughts guys; Pav, I have also built a couple of surfboards, but may well be after some pointers I'm thinking kevlar/glass "Aramat" with Vinylester resin.
Magpie, good point about the stability, thanks. the waterplane area and max' beam is the same as my smaller sit-on, so about as stable - I can kneel up to paddle that one. I probably have made the manakin look a bit high in the picture tho.
Glowworm, it'll be a while before I start building (need to find a workshop first!!) but if i have a mould then it'll be available for others to use too.

 

[Magpie]

He's high? Ah that would explain the funny expression!

As I said before mate, if you need a test pilot...(What SOTs have you got already?) Kevlar? Might as well sod it and go carbon I reckon, you wanted it light after all rofl

 

[foxfish]

Jonny your idea is sound although i still feel a swim float is a better option?
I have built my fair share of boards but it would be fun to own something like this Atlantic Waveski

 

[Jonny250]

Hey Foxfish, you wanna have a go on my waveski then! atlantic are developed by guys who taught me to roll my ski (I still cant roll properly). a february lesson off Croyde bay - very chilly! They are serious fun in mid size waves, when there's not too much white stuff around. You would be very welcome to have a go on mine - it's brilliant!
Magpie, I have a perception scooter and the perception scooter tandem - both for sale...

 

[Magpie]

Ah right, thanks but no interest, I'm after something with a lot better tracking and speed, at the moment I'm being far too tempted by one of these:

Kayak UK - home of Kaskazi Kayaks in the UK

But will probably never happen....

Anyway, back to the subject, the open stern is a great idea for diving. Have you thought about gear storage? You say the front is a fishbox, so what about guns, fins and importantly, weightbelt.

Will need a flag of course, and anchor points. Do you know what an anchor trolley is? Actually, thats more relevant for a fishing yak than a diving one.

How about a colapsable sail? This lot are a well known brand/design Pacific Action sail systems for kayaks and canoes

 

[sunfish]

at the moment I'm being far too tempted by one of these:

Kayak UK - home of Kaskazi Kayaks in the UK

But will probably never happen....

Never say never. They look a bit pricey though. Where are they made?

 

[foxfish]

Jonny I had a bad experience with my surf ski back in the eighties when in turned over at centers reef & I couldn't undo the "quick release" straps. I also surfed for a few years on a kneelie board.

 

[Jonny250]

Foxfish, I know what you mean about the 'quick release' its a bit scarey and I dont tend to clip in; love the ski tho.
Magpie, that looks like quite a sit-on, but it's 26kg! nice and streamlined, good tracking, etc tho. Cool sail system too.

 

[Magpie]

Virtually all decent length SOTs are around that weight. Scupper Pro, Prowlers, Tridents, Malibu X Factor, Explorer and Extreme, Perception freedom, RTM Disco and Tempo (Scupper), they're all 25kg or more.

They're South African Sunfish, thats the site of the UK importer. Pricey, yes, but that price includes a lot of extras that you buy ontop of other SOT prices, like rudder and rod holders and decent hatches. Its fibreglass not plastic too, on and its the dogs...

 

[foxfish]

Some of the very first underwater spear fishermen were surf dudes, they used their longboards as floats as documented is some of the great spearfishing books where you can see pics of huge fish lying across their boards.
I think these guys would simply paddle out as you normally would on a surf board, with your hands.
I have seen guys in the Cape Verdi Islands using canoe paddles on long boards, they were just kneeling on the board that also carried a fish box & gun. I have some pics of these guys somewhere but I think the logic behind the boards is so that your body is out of water when you are making your way out to fish & safe from sharks.

 

[Pav]

I used to consider buying or getting a free windsurf board from the dump. The massive ones that no one can seem to sell! , so they are often given away. I'm sure with some imagination you could adapt one.

 

[foxfish]

Construction : If home made its GRP from a mould or I am pretty sure you can get large foam blanks which are destined for windsurf boards. You may have to put in your own stringer?

QUOTE]

Pav I ment to say you can buy 8'x4' polyurethane sheets in thicknesses up to 6'' (2.4 x 1.2 x 150mm)

 

[settingsteel]

Great thread, should be interesting to hear input/progress...Fox very cool website...

 

[catman]

That´s what i call massive diy.
I've never used one, but from the designs it seems that you have spent some time thinking. I really like the low transom idea. I would include some strapping points for carrying the guns and also a watertight compartment to store water, doc's, and some food for the journey. Just don´t forget to include a flag pole.

 

[settingsteel]

Haven't googled it yet...but I saw at the Miami Boat show yesterday a hand held steerable, motorized surfboard...video showed the guy standing up holding a flexible tube (used to steer), on a surfboard that had a small motor on the back very quool:martial

 

[mishnish]

Maybe this is resurecting an old thread, but I have serious plans to design and build exactly what is being discussed. I am a naval architect by profession and I would be happy to provide my design knowledge to the problem. It is likely that my build material will be 3mm ply stitch and glue to realise the lightest weight for the least cost. I have a rough 3d model and would be willing to post renderings to those interested in developing the idea. Perhaps we could even come up with a drawing/build pack and offer the pack at low DB prices. For me this will likely be a winter project as I can not justify sitting in front of my computer while its sunny outside!

Let me know what you think