Selway Fisher Stitch and Glue Dinghy - Simplicty 8

[Monzu]

Hi all,

I thought I'd start a thread for my first attempt at making anything boat related. I've been browsing the forum and daydreaming about boat building for a fair while, but in a decidedly uncharacteristic move, I decided to start small and simple. The plan is to build a Selway Fisher Simplicity 8 dinghy to serve as a tender to my 18" yacht which is kept in muddy Essex (UK). I was after something that could be built from single sheets of ply, and would serve as a good introduction to ply boat building. I'll initially build it for rowing/motoring, and may build the lug rig at a later date.

Link to Simplicity 8 dinghy:
http://www.selway-fisher.com/Otherupto10.htm

So far I've cut and planed the main panels to size and stitched them together with copper wire. After a couple of hours of fettling, the seams have closed up with a couple of minor gaps (which I imagine are within tolerance). The central bulkhead is in place and also secured with copper ties. Unfortunately, the weather has just taken a turn for the worse and is unlikely to be above 5 degrees Celsius (41 Fahrenheit) for the next week or so. I'm using West 205 fast hardener which I understand has a minimum curing temperature of 5 degrees. Hopefully I'll get a chance to start applying thickened epoxy fillets next weekend.

Here are a few pictures of progress so far.









This is all very new to me so please feel free to point out any glaring errors!

[bluedog225]

Looks great. Welcome!

[CaptainSkully]

Nice! My first boat was an 8' pram. I'm sure there are lots of other parts you can start making that don't involve epoxy. I always try to have bench projects ready for when epoxy is not an option or it's curing.

[Monzu]

Made a little bit more progress. I've mostly been mocking-up the bulkheads waiting for a break in the weather to use epoxy.

Here are the main bulkheads held in place by clamps and screws. I've not followed the plans to the letter as I wanted to incorporate built-in buoyancy to remove the need for carrying buoyancy bags. I may live to regret going off-piste but it seems to be working so far.






The arrangement for the forward bulkhead looks slightly counterintuitive but I think it makes sense. The timber cross piece in the plans in 50x22mm and forms the upper mast support. As the mast is raked back at a ratio of 150 to 2000mm, depending on how you make the mast gate, part of the mast would be resting on the lower edge of the timber support which doesn't seem ideal. Furthermore, I can't mount a ply bulkhead (not drawn in the plans) to the aft edge of the timber support as it wouldn't allow for the mast rake or the provision of the mast step. I therefore calculated how much the mast's leading edge would project forward at the mast step due to its rake, added it to the thickness of one half the mast step, and made up a new timber support in this thickness (55mm). The ply bulkhead will therefore be vertically attached to the forward side of timber support. I've also beveled the aft side of the timber support to the calculated angle (somewhere around 5 degrees from memory) to provide a better bearing surface for the mast leading edge. Hopefully this makes sense. I've attached a quick sketch of the plan with the mast rake exaggerated for clarity. Let me know if I'm making a daft error.




Here's the mock-up.




This image shows the ply knee in place. Excuse the mess of epoxy in the bottom right. I managed to put a crack through a couple of veneers across the corner of the plywood. This is the result of injecting epoxy into the crack followed by fairing the surface with some thickened epoxy.

[Monzu]

Little bit more progress. I flipped the hull over and started working on the underside. So far I've filled the outside seams with thickened epoxy and planed the joints at the fore and aft transoms in preparation for applying fibreglass tape. The plans only suggest taping each of the seams on the outside, but knowing that the boat's likely to see a bit of rough use, I'd prefer to sheave the whole bottom. Should I tape the seams initially and then go over the top with a single sheet of woven glass, or go the other way around (i.e. single sheet first and then follow up with tape along the seams)?

Here's a shot along the centreline before I filled the seam with thickened epoxy.




Quick shot of the transom/bottom plank joint after planing.




The boat as it stands.

[figo]

Nice job! I've been looking at plans for a small dinghy as well. I like this one.

[Monzu]

More progress now the weather is warming up a bit.

Daggerboard case mocked up. Before gluing it all together I coated the inside surfaces with two coats of epoxy and two coats of paint.




Here's a shot of the inwales going in. There made of 35x15 sapele. Pretty difficult to bend into shape single handed when they're covered in thickened epoxy. It's nice to see how much the hull is stiffened up by the addition of the inwales. I've also mocked-up a small inspection port for the centre thwart buoyancy.




Sapele trim at the top of the front transom. I'll plane the top edge to match the sheer at the gunwales once its glued in place. The photo also shows the thwart top rested in place. Annoyingly I've now run out of 6mm ply with only the middle and aft seat top to do.




Here's a general progress shot. Just need to and fasten all the trim sections, attach the outwales, fit the seat tops and then it'll be ready to flip over to finish the bottom.

[Monzu]

Well, I jumped ahead and starting working on the bottom of the boat just for a change.

Following the guide holes I drilled from the inside of the boat, I cut out the rest of the daggerboard slot. Actually not as scary as I thought. It also ended up exactly centered and aligned with the panel seam, which was pleasing. Here's a picture of the rough cut after jigsawing, but before sanding a radius on the edges.




I then sanded all of the seams in preparation for applying fibreglass tape.








Quick question about sheathing. What type and weight of fibreglass cloth should I use? I seem to keep bumping into conflicting advice online.

The main parts left to do on the outside are sheathing and to fit the skeg and bottom runners. I'm hoping to make a start this week.

[Monzu]

I finished taping the outside seams which didn't go exactly to plan. The temperature was still quite low so the epoxy was fairly thick. As such, I ended up applying more epoxy than required in order to ensure that the tape properly wetted out. Although I have no concerns with the strength of the joint (it did ultimately wet out), it didn't go on as smoothly as I hoped and required a fair bit of sanding a little bit of fairing compound to smooth over.

I then went over the bottom panel in one layer of 200g cloth. I made sure the hull was pre-heated, as was the epoxy, and got a much better result than with the tape.






Next up was the skeg. It's made out of 9mm ply with 15x15mm sapele supports either side. It was a bit of a pig to bend it into place and secure it. Definitely not a job that can be done alone. Managed to epoxy and secured it with screws from inside the hull. I finished it off with small epoxy fillets down both sides. Just the bilge runners to do before the hull exterior can be painted.



The image above also shows the sapele outboard mount that I attached to the hull. I didn't fancy mounting a jagged outboard bracket directly to 6mm ocoume plywood.

[Monzu]

The gunwales are largely finished. Just final sanding and shaping to do. I don't have a photo showing it but the screw holes have now all been plugged. I've also added small supports for the rowlocks which have been dry fitted.










I ended up rebuilding the front thwart in 9mm ply. My thinking was that once I'd fitted the two inspection ports (which were too large to be fitted to the vertical bulkhead) that the structure was weakened and could be damaged if sat on heavily. I backed up the two openings with 6mm ply rings which were bonded to the underside for additional support.




Not too much left to do:
- Make and fit centre and aft thwart
- Fit bilge runners
- Fit inspection ports
- Sand and epoxy entire interior
- Paint hull, inside and out
- Varnish gunwales

[CaptainSkully]

Wow! Great first build! You've done an amazing job. Thanks for sharing your progress pics!

[Monzu]

Thanks! Feels like the end is in sight. Managed to fit the bilge runners yesterday so only a general sand and the off bit of filling and the exterior of the hull can be considered finished.

[Monzu]

Really starting to get there. The bottom of the boat is finished, save for a quick sand and some paint. You can just about make out one of the bilge runners in the image below.




Inside the boat, I finished cutting out and mocking up the middle and aft thwarts.










Other than securing down the thwarts, all that's really left to do is a whole lot of sanding and preparing before paint. I'll launch the boat is rowing trim and then finish building the sailing rig when I've got more time.




I'm already looking back at aspects of the build with disdain. There are plenty of things that I would do differently if I started anew. It's certainly a rapid learning experience building a boat! Can't wait to get it finished (which I've no doubt will take far longer than planned).

[WHYankee]

Bravo!

[Monzu]

A few more shots of the progress so far.






I diverged slightly from the plans again and added a centre strip of sapele forward of the daggerboard slot. The dinghy is likely to see some rough use and the forward centreline seems like a vulnerable point.






This morning I started painting the buoyancy tanks and the underside of the thwarts. Few more coats and the thwarts can be glued down. That'll be the last piece of actual construction, everything else will be paint or varnish.

[Monzu]

Well, I've been marching ahead with the work but forgetting to keep you all updated.

So, to bring you up to date...

Last of the gluing complete.



Undercoat



Topcoat, which I rolled and tipped. Could definitely have been better but looks reasonable from six feet.

[Monzu]

A whole lot of varnishing later and it was ready to launch.






This is launch day. Popped it on the car roof and drove it down. Not too bad with two people getting it up onto the roof. Certainly easier than having a trailer and working out where to keep it.




Quick shot of my wife and I on launch day.


It seemed to row really nice and track in a straight line. It also motored well with my British Seagull 40+.

[Monzu]

I also made a start on the mast. The plans specified that it should be 2850mm long and 50mm diameter at its widest point and made of 'spruce or pine'. I was unable to find much in the way of appropriate timber that was local to me (London, UK) and ended up buying what was listed as 'yellow pine'. Considering how dense and stiff it felt and the contrasting colour of the summer/winter growth I took that to mean pitch pine. Given it seems to be heavier than specified I ended up laminating up two pieces and making a mast that was 45mm diameter overall (instead of 50mm) to try and save some weight. No idea if I've ended up with something suitable or just wasted my time. Would love some input. Good practice either way. I don't suppose anyone knows what kind of weight a lug rig mast should be for a dinghy of this size?

Here's the timber:

[Monzu]

Marked with a spar gauge:





Kept square in profile at the bottom for the mast step and support.





Another question mark - have I excessively weakened the mast by installing a halyard sheave?

[amish rob]

I don’t think you needed a sheave for that small a mast and sail, but you’ll be fine. I wouldn’t worry after that.

Looks like very neat and careful work, which counts for a LOT. The material itself looks fine.

Have a great time with your cute, wee boat!

Peace,
Robert

[Oldad]

Should be fine...

[St.J]

Nice job.
is that the River Lea? Near Stamford Hill? Or am I miles out?
St.John

[Monzu]

Nice job.
is that the River Lea? Near Stamford Hill? Or am I miles out?
St.John

It is indeed. Well spotted! Are you local?

[St.J]

Finsbury Park.
My wife used to live on Watermint Quay!
Building small boats in small garages is something I can associate with....

[Andrew2]

Ah, nice effort!
My first little boat was similar, but much rougher and flat bottomed. Sailed and rowed her on the Lea at Broxbourne.
A2

Edit: The blue Redshank in the link, 'Black Pearl', was built by a friend just down the road for his grandson.

[Monzu]

Thanks for the kind comments. For anyone local, you may see me rowing by one day...

[Monzu]

I'm now slowly working on the rig. Instead of buying cleats for the mast I thought I'd have a go making some. I've got a big chunk of oak worktop that I found in a skip. It's made of 2" square battens glued together which made the ideal stock.

I copied the shape of a nylon cleat, which on reflection, is probably not ideal. I think they've got too much curve on the upper surface, although considering the minimal loads that they'll be subject to, I can't imagine it'll be a problem. I'll mark it up as another lesson learned. The cleats were made using a coping saw and files. Took as few hours but came out well.

The photos show them with 1 quick coat of boiled linseed oil.

[Monzu]

More slow progress. We're moving out of London in mid-August (heading to Edinburgh) so lots of distractions over the last few months. I've been picking a choosing little fun jobs on the dinghy rig whenever I could get the chance.

I've made a bit more progress on the spars. I managed to find some very nice Douglas Fir in place of the Southern Yellow Pine of the mast. Here are the two pieces for the boom glued up:


As the images below show, pieces that are close to plain sawn show wavy grain whereas the edges show dead straight grain. The second image shows the two pieces laminated together after having the top face planed. The centre line is the glue line, the outer lines are pencil marks.




I definitely found the fir quite hard work when hand planing. The grain has constant slight undulations over its length, despite being relatively straight, causing small amounts of tear out within the soft summer growth regardless of which direction you're working in. This effect is compounded when two pieces are laminated side-by-side and have to be planed together. It may just be my inexperience, but it wasn't easy and required a fair bit of sanding to correct mistakes.

Here are few shots of the almost-finished yard. It tapers from 20mm, up to 45mm and then back down to 20mm. Really pleased with the finish, though it seems impossibly slender (though built to the plans) but is remarkably stiff.


Here it is with octagonal profile. I used a spar gauge and hand plane to get to this stage.


Here it is fully shaped.



I’ll omit posting photos of the boom, as it’s straight-sided and not too exciting to look at.

[Monzu]

I affixed the oak cleats I made a few weeks ago to the mast after they received some boiled linseed oil.







Finally, I got started on a job that I'd been mulling over (and secretly dreading) for the last few months; building the partners and step for the mast. My main concern was trying to get the mast exactly vertical in relation to the hull and with the correct amount of rake. The rake was given in the plans as 150 in 2000, which, after brushing off the cobwebs off my secondary school maths, I calculated as somewhere around 4.3 degrees. I actually worked this out earlier in the build and cut the forward thwart supporting beam to have a 4 degree(ish) bevel on the after face so that the mast would sit nicely supported against it.

I built mast partners out of some scraps of sapele and secured them in place with four #8 50mm screws per side and plenty of thickened epoxy. Should be a lot stronger than the 3mm x 20mm brass strap suggested in the plans. The idea is to make a pair of oak pins (a bit like belaying pins) to sit in the holes and use them to lash the mast into the partners. I looked at a few different ways to securing the mast, but figured that lashing would be simple, fast, and would leave the forward thwart uncluttered when the rig isn't fitted.

[Monzu]

After securing the partners exactly amidships, I started working on the mast step. It's made of four layers of 6mm okoume, laminated with epoxy. I then routed the mast slot back through three of the layers, to leave a 6mm cap on the bottom. Before mocking up the mast, I levelled the boat fore-and-aft to establish the datum as per the plans and then levelled it side to side. I then used spirit levels and a digital inclinometer to establish the correct position for the mast step to ensure that the mast was straight and correctly raked. I then slathered it in thickened epoxy and chocked it in place with the mast secured in its step. Having measured it another fifty times, I carefully tip-toed out of the garage, slowly closed the door (I couldn't possibly allow the slightest disturbance of the air!) and left, hoping that nothing would slip overnight. Well, I got lucky and the mast seems to be dead straight and raked by 4 degrees. The mast step will be supported on both sides by wedges of sapele, filling the space between the step and bottom of the boat, and larger epoxy fillets all round. I’ll leave a small channel beneath the centre of the step for drainage.









Here’s a mockup of how the lashing arrangement will work. Obviously it’ll be secured with more line and the pins won’t be scraps of white pine.




Next up, I'll finish varnishing the boom and yard, finish the mast step and make the pins for lashing the mast. Making the daggerboard and rudder may well have to wait until I get to Scotland.