Building a Streaker from the CAD plans Experiences of an amateur boat builder

Preamble

When my eldest son went off to University it was clear that my beloved had to go, as the tame crew was no longer going to be available. So in 2009 I tried out the obvious single handers;

Laser -too uncomfortable, horrible contrived sail controls, nasty 78 degree rudder and weather helm. Centre/ transom mainsheet catches around the transom and rudder. Expensive poor quality one design sails etc. etc. Basically just too much like hard work at my age.

Solo – too heavy for me, too expensive for a competitive one, too difficult for an amateur builder to build a competitive boat. Big sail area tended to overpower me in anything above force 4. Big plus for me though is pure centre main.

Streaker – Light, responsive, ideal for my weight and height and can build a competitive boat for circa £2000 but alas - no pure centre main.

Then in 2010 the good news came along that the SCOA changed the rules to allow pure centre main, so then there was no contest for me and I decided to build a Streaker. I had bought the wood but then found out that the SCOA were preparing CAD plans for the boat, so I decided to wait until they were available.

It wasn’t then until the winter of 2011/12 that I finally got down to building the boat.

There are good instructions on how to build the boat that come with the CAD plans. I don’t plan to repeat all that detail here. This article is really intended to cover the things the plans don’t say and my experiences (including mistakes) as I went along.

Printing the plans

The plans came on a CD and were in AutoCad format. To print them full size I needed to find a print shop that has the AutoCad software. None of my local printers could do this. Eventually my friendly neighbour who is an Architect printed them out for me. It’s possible to convert the plans to pdf format if you have a copy of Acrobat Pro. It is a lot easier to get someone to print from this format. The only caveat is that the conversion is not always 100%. Either way you may need to budget about £100 for the print run.

Aquiring the materials

Unless you are an experienced boat builder selecting the right wood for the different parts requires a bit of research. It’s easy to use traditional boat building materials but it’s also easy to end up with quite a heavy result. Selecting wood which is light, strong, resistant to rot and flexible where it needs to be, is not so straightforward. From my experience the choices are as follows:

Deck supports = Western Red Cedar or Douglas Fir Keel (or Spine) = Western Red Cedar (Light) or Sapele (Heavy) Gunwales = Obeche (Light) or Ash (Heavy) Plywood = Robbins Elite (expensive) or Other Marine ply (maybe cheaper)

I used Ash for the Gunwales as it is very tough and easy to bend but it is part of the reason my boat is overweight. I have no experience with Obeche but I am told that it is very good and much lighter. You need to track down a timber merchant who can supply it in lengths over 4m if you want to avoid scarf joints. Western Red Cedar (WRC) will be OK for the Keel except it may be more susceptible to wear from you feet and other knocks in the cockpit area as it is quite soft. I didn’t use WRC anywhere that I needed to bend it, as I wasn’t confident of its bending characteristics. For the Plywood, Robbins Elite is the safe choice as it is very high quality marine ply. The batch of wood used and therefore the final colour varies from month to month so it’s important to buy all the ply you need at the same time. It’s possible to find marine ply up to 50% cheaper but the quality of veneers may not be so good. Robbins offer more decorative plywood for decks etc. but always at the cost of more weight (& lots of money!). WBP ply is almost the same as marine ply (uses the same sort of glue) but it typically has voids in it and shouldn’t be used for boat building.

Screws bolts etc.

There are a lot of companies doing A4 stainless nuts bolts washers and screws on Ebay these days and if you buy in quantity it’s dramatically cheaper than Chandlers prices.

Glue varnish and paint

Modern epoxy resins are definitely the way to go for the adhesive and for coating the bare plywood. The same resin is used for clear coating, gluing , filleting and filling. The resin is modified for each job by means of additives which are mixed with the resin. There are a number of different brands available each with their claimed advantages and disadvantages e.g.:

West System – long track record for boat building – fairly foolproof especially if you use the measuring pumps. The epoxy is nasty if you get it on your hands and it’s not UV stable so has to be covered with varnish. I’ve had some problems with a white bloom in clear coated areas but I think it was actually due to moisture left over from wet/dry sanding. A big advantage is you can use it down to 5 C which is essential for a winter build in an unheated garage.

SP systems – claimed to be better for clear coating than West. More expensive. Not UV stable. Needs 15C ideally

Sicomin – I’ve not tried this yet but it’s claimed to be UV stable and not nasty if you get it on your hands. Also only suitable for use at higher temperatures. If you are building in the winter you need to use the right hardener (fast) if you are in an unheated garage. Even the fast hardeners struggle below about 10C. In the summer you’ll need to use a slow hardener or you will have very short working time. Watch out particularly for mixes with filler powders in them – they can get very hot and go off very fast and even burst into flames if you mix up too much at once!

For paint I used two pack epoxy and two pack polyurethane Varnish. Traditionally most people would use International paints and its very good stuff but also very expensive. I used Jotun paints and Jotun hardglaze varnish. For the basic colour range it’s about half the price of international. The downside is that the colours are a bit industrial. (Think north sea oil rig!) I found both the paint and varnish to be totally compatible with West Epoxy

Tools

I bought a table saw as I bought all the wood I needed cheaply as fairly big offcuts and sawed it all down to size myself. The table saw definitely paid for itself on one boat.

It’s not possible to have too many G clamps. They are fairly cheap to buy from the online tool stores. Some sash clamps for attaching the gunwhales are a must as well some one handed pistol style clamps. Otherwise a good selection of spring clamps and some bricks wrapped in clingfilm to hold things down are useful!

A power plane is very useful although not absolutely essential.

I used a belt sander to make the (many) scarf joints. It may be possible to do it with a power plane but I’m not clever enough to do it. You need a good powerful belt sander for the job. Its a very dusty business. You must wear a dust mask.

You need a 1metre long straight edge for marking out.

A good power jig saw is a must. Experiment with different saw blades. I found the metal cutting blades best for cutting ply without splintering the edge.

Otherwise you need a good selection of standard wood working tools.

Consumables

I got through a huge quantity of paper mixing cups, wooden spatulas, disposable paint brushes, sponge paint rollers and latex gloves. It really isn’t feasible to clean utensils when you are working with epoxy because often by the time you have finished the job in hand the brush is set rock hard.

Fortunately the online suppliers of fibreglass supplies sell all this stuff in quantity at very low prices. Frankly it’s very hard to find paper cups anywhere else these days and the plastic drinking cups you can find in the supermarket are no good as they melt. Just google Fibreglass supplies and you will find the right people. Get your Epoxy from these guys also.

Space

You need a space to build the boat in but you also need a space that you can lay down an 8 by 4 sheet of ply and an A1 drawing to it out. If you are limited in space then it may be best to mark out all the parts and cut them out before starting to build the boat. This would then put the scratch builder in the same situation as the kit builder. The disadvantage of this is its easier to store full 8 by 4 sheets rather than many small cut out parts. Also its easier to cut out the parts just before you use them. Once you can see the shape and size of the deck from the half built boat, it’s very confidence building when you have to cut out the part, especially if it’s expensive one side Sapele veneer.

Marking out

Marking out the ply is pretty straightforward. The plans show the shape of the panel and there is an offset table from which you can set out the shape on the ply. You then “join the dots” to complete the marking out of the panel. It’s a good idea to coat the finish side of the ply with Epoxy and let it dry before you cut it out. This protects decks panels etc from scratches and marks during the building process. If you spill anything on it you can just wipe or sand it away. It does mean you use some extra Epoxy to coat wood that will ultimately be scrap but on the whole it’s a good idea. If the parts are stored for a long time before use you will need to sand any previously epoxied areas that are going to be glued. If you have pre epoxied the sheet of ply then you want to mark out the bare wood side and cut the same way up so that the jig saw leaves a clean edge on the epoxy side. Be careful with “handed” parts that you get them the right way around so that the finish side will in fact end up on the outside.

Building the Keel

Having done some epoxy coating and cutting out some panels and maybe doing some scarf joints in the panels, I really couldn’t put off starting to build the boat proper any more.....

Building the keel is the most critical thing in the whole build process and it’s the very first job! The keel essentially defines the ultimate shape of the boat. If the keel is wrong then the boat will not measure as class legal. Fixing an error in the keel once the boat is finished is almost impossible. You have been warned!

Setting out the keel accurately in accordance with the instructions in the plans is therefore essential. The method is to draw a dead straight line on a level floor and to measure the offsets from this straight line. The spines and the centreboard case were clamped with G clamps whilst the assembly dried. It was therefore necessary to chock up the assembly off the floor so that there was room for the clamps. It’s difficult to keep the whole thing straight and keep the measurements accurate like this. Maybe there is a way to do this so that the centre board case can lie flat on the floor. I couldn’t work it out. The overall rule anyway is to measure and check and check again. Once the assembly is dried you should check the measurements and check the spine is straight before proceeding any further. Better to scrap the thing and start again rather than build the boat wrong.

It’s worth noting that the Streaker kit comes with the centreboard case and spine pre- assembled so if the above puts you off, its worth considering the kit as an alternative.

Boat Options

Before proceeding further I had to make some decisions on some of the options for the boat:

1. Centre main or not – centre main for me – affects reinforcement of tanks before decking

2. Open forward cockpit – need to change the bulkhead slots to accommodate -see below.

3. False floor or not – false floor is the norm – need to decide how far back along the centreboard case to bring it – see below.

4. Curved or straight thwart – curved allows you hike further forward comfortably.

5. Aft tank drain tubes – see below

There is now a sixth option which wasn’t available to me, which is the long or short aft tank. I’m sure all new boats from now on will go for the short tank.

Centre Main

As previously noted pure centre main was a no brainer for me and I haven’t regretted it. It should be said though that with this option it’s not so easy to achieve optimum upwind boat speed. To get the best performance upwind you want to use the mainsheet to bend the mast rather than the kicker. With centre main you will tend to pull the boom too close to the centreline of the boat if you get enough main sheet tension. A traveller track would solve this, but because traveller tracks are not currently allowed in the rules, I allowed the lower mainsheet pulley to travel on the bridle between a couple of rope stoppers about 10 inches apart and this seems to work fine. In terms of the build for pure centre main you need to add a reinforcement pad in the side tanks behind where the thwart is attached to increase the strength of this structure. A U bolt is then bolted through the pad. This is where the mainsheet bridle attaches. The bridle feeds through apertures cut in either side of the thwart. I positioned my U bolt further forward because I hadn’t thought about going through the thwart. It still works but I could have reduced the reinforcement I used.

Open Forward Cockpit

This is one of the innovations to the wooden boats that Dave Butler developed. In the original plans the aperture into the forward part of the cockpit is restricted. In Dave’s version the aperture goes right back to the side tanks. This looks much better and there is no disadvantage as far as I can see. In order to do it this way you have to change the slot and tab arrangement of the bulkhead and the tank sides. In this version there are no slots in the Bulkhead and a slot top and bottom on the tank sides. The bulkhead is cut out with an aperture that forms the support for the false floor at the bottom and has the side tanks against the side and the deck beam at the top. The first task in assembling the boat is to feed the two side tank panels though this bulkhead and push them back against the sides so that the slots engage. You have to think about it and measure it out carefully as the plans do not cover this option. Once the side panels are slotted into place the rest of the bulkheads and the spine can be slotted together per the standard build method.

False Floor

If you sail only on inland water it’s debateable whether you need a false floor or not. It makes the boat harder to build down to weight and the main benefit of preventing nose diving in waves after a capsize won’t be of any benefit to you. Building the false floor also takes a surprising amount of time.

On the other hand virtually all modern Streakers have the false floor and any boat without it would have a restricted market as a second hand craft. Also the false floor framing really stiffens up the front of the and the centreboard case.

I therefore decided to install the false floor but the next question was how far along the centre board casing to take it. I decide to install the false floor full length along the centre board case. In retrospect the best decision would have been to only take the false floor about half way along the centre board casing. This gives virtually all the advantages of stiffness and allows the self bailers to be positioned further forward away from the helmsman’s feet and also at a better draining point in the hull shape. Its also probably less weight although with longer floor battens needed there is not much in it.

The plans say you can make the false floor from 3mm ply. This is fine, although I wouldn’t recommend standing on it if you do! There are definitely times when you want to stand in this area so I went for 4mm ply and had to put up with the extra weight again.

By the way, although the plans do show dimensions of a false floor the reality is that you have to make this fit your boat as built. The only way to get it to fit is to make a cardboard template and cut the floor out from that.

Before decking over the false floor you need to decide if you want reinforcement pads for the toe straps. In my case the Toe straps screw onto the back edge of the false floor. If you go for this, make sure you measure or photograph where these are before you put the deck on. I forgot the exact position and missed the pads with my first attempt. I ended up with some annoying holes blocked up with filler as a result. It’s possible to attach the toe straps to the thwart and/or centre board case if you prefer.

Curved Thwart

Another one of Dave Butlers innovations. I went for a curved thwart and made mine form laminated strips of various woods. It looks very nice but it is much easier just to cut it out from ply and cap the edges with some hardwood. You are allowed to cut lightening holes in it. These make very good grab handles for pulling yourself back into the boat after a capsize and are needed to feed the centre main bridle through (see above).

Aft tank drain tubes

When I built my boat I didn’t realise this option was allowed in the rules. I would strongly recommend installing these. Without these the only way the cockpit drains when the boat is under its cover is though the self bailers. It’s very difficult for me to store my boat level and it naturally wants to be bow up, so the tendency is for water to build up at the back of the cockpit. Somehow the rain always gets into the boat. I’m not sure how – presumably down the mast where the cover doesn’t fit perfectly. With drain tubes through the aft tank the boat could be stored bow up and guaranteed not to fill with water. For a future build I’m thinking about 2 X 1 inch fibre glass tubes epoxied into the aft tank. With the short aft tank this is only about £15 of fibreglass tube. I’m told Epoxy sticks to standard polypropylene pipe, but I’m always a bit suspicious of the quality of bond to these “greasy” plastics. Whatever you use it has to be strong and seal for good of course. These tubes would also act as “transom flaps” to some degree. Some non return flap on the outside of transom may be needed though so as not to get water back in when you are fitting the rudder etc.

Short aft tank

For me this is also a no brainer for a future build. The Streaker is massively over provided with buoyancy tanks so losing a bit of volume here is no problem. The longer cockpit allows easier stowage of the boom when travelling and less deck material will make it easier to built the boat down to weight. The modifications to the plans for this option and the rule changes that allow it have been issued. The original bulkhead is be retained inside the side tanks only and there is an additional bulkhead required which now forms the back of the cockpit. For stiffness this probably needs to be extended into the tanks as well. In this option the toe straps probably will be fixed to the spine directly rather than on a bracket bolted though the aft bulkhead. The floor battens obviously need to be extended to stiffen the extra expanse of floor. With this option the dilemma of how to fix the rudder fittings to the transom will be moot. On a standard boat it’s well nigh impossible to reach the bolts inside the tank once the deck is on.

Since I built 1770 the class has allowed a double thickness floor instead of the battens traditionally used to stiffen the floor panels. This is a big improvement and makes the boat quicker and easier to build and definitely makes the floor stiffer. I’ll describe how this is done in a later article. Hull assembly build

I supported the hull assembly on two trestles positioned under the fore and aft bulkheads of the cockpit. I cut out matching curved supports from chipboard which I screwed to the trestles. This supported the boat nicely throughout the build whilst the hull is upside down.

One observation on the cutting out of the bulkheads: Make sure the bottom edge of the bulkheads where they attach to the hull are dead flat or very slightly convex. If they are concave then you will get hollows in the floor panel which you will need to fill with fairing compound.

Once the side tank panels and the bulkheads were glued together the spine and centreboard assembly was laid into the matrix. The back end of the spine has to line up with the back of the side tank panels so that the transom fits on all square. If the parts have been cut out accurately all this slots together very straightforwardly.

The next stage was to fair the spine and centreboard case so that the hull panels fit on nice and flat and meet squarely in the middle along the spine. I used a surform for this job. Everything I had read about building the Streaker said that joining the bottom panel at the bow was going to be difficult. Obviously the ply is very tortured to be twisted into the bow shape but by using copper wire tourniquets it’s very easy to control the shape how you want it. The holes made for the tourniquets are just filled up with epoxy micro balloon filler later. The two edges of the panels are held together with wire ties per instructions. I left all the wires in until the complete bow was finished. The typical way to hold the panels to the bulkheads during gluing is to use a staple gun. I actually found it quite difficult to get the staples into the middle of these very thin panels. I missed quite a few times but any damage was covered up with epoxy fillets or paint etc later. The staples are easy to remove once the glue is set.

It’s worth noting in the picture the use of a piece of timber pushed through holes in the bulkheads to hold the parts of the bulkheads for #3 and #4 bulkhead in place while they are being glued. It’s very hard to clamp them any other way.

In contrast I found the chine panels much harder to do and I couldn’t get them very level. I had to fair the finished bow off quite a lot with filler.

Wiring the floor panels to the side bulkhead panels is a little tricky if you don’t want the wire holes to show inside the cockpit. The epoxy fillet will cover them if you make sure they are close to the edge of the ply.

Topsides Build

Once all the hull panels was assembled and the glue had cured properly I took out all the wires and filled up all the holes. You will read about heating the wires with batteries to get them out. I found they all came out pretty easily by rolling them around the nose of a pair of pliers.

I then turned the hull over. I checked the hull for twisting and also checked all the beam measurements to make sure the hull matched the measurement form. It’s very easy to check the sheerline beam measurements at this stage because without the deck on you can see the sheerline. I found I had to wedge between the temporary #4 bulkhead and the side bulkhead to get the beam measurement at this point right. Otherwise everything seemed to measure OK and the hull was nice and straight.

The next job was to glue in the triangular piece of wood at the bow that the bow plate screws into. This piece of wood has to hold screws really well as you can’t really bolt on the bow plate, so I think it worth using something like Sapele even though its extra weight. After that the inside seams of the hull panels were taped with fibreglass tape and Epoxy. I used 50mm tape because I think that’s what was used in the Streaker kit. I probably overdid the amount of Epoxy on the tape and could have saved some weight here.

After that came one of the more daunting jobs which was to fit the gunwales. I used a single 4m long piece of Ash which was simply bent glued and clamped to the top edge of the plywood hull. It’s actually not necessary to use any screws at all especially for this first stage of the gunwale when the deck is off. I did use a couple of screws temporarily while the glue was drying and then took them out. The only tricky bit to clamp is at the bow as the clamps want to slide off the opposite side of the bow. I just used a temporary screw into the bow to stop the clamp sliding. Once the gunwales were on the tops of the ply were surformed off until I had a level surface to glue the decks on.

When the decks were cut out they were obviously larger all round than the actual decks on the boat. The foredeck was glued on in single piece and then cut back to the actual deck dimension with a jigsaw and then with a surform. The same principle was used for the aft deck.

In case of the short aft deck it might be just possible to use a single piece of ply. It’s actually very slightly wider than the standard sheet of ply so it would have to be cut at a slight angle and getting the grain straight could be tricky. It wouldn’t work for stripy sapele for example.

Before fitting the decks it’s important to make sure any reinforcing blocks that are needed for fittings are installed. (e.g centre main, toe straps, control cam cleats, shroud plates etc). I also had to coat all the inside of the tanks with epoxy where they weren’t coated already.

I generally ended up making all these reinforcement pieces tougher, bigger and stronger than they need to be. On its own each one of these pieces of wood doesn’t seem like much and when you think about the load that will be applied, it’s tempting just to beef it up that bit more. The trouble is it all adds up....

Clamping the decks down for gluing wasn’t easy as the clamps tended to slip off the gunwale. Think about the profile of the gunwale before you glue it on with this in mind. The decks also have to be coated with epoxy on the whole of the inside before they are glued on. (The outside was precoated with epoxy before cutting out.)

With the foredeck and aft deck glued on, the ends of the side decks were gently sanded down until they just popped into place still exerting a bit of pressure on the edge of the foredeck and aft tank deck. This was a long winded process but if you want a perfect gapless joint there is no other way. It was at this stage I made my first major mistake. I didn’t get the bulkhead level where the side decks met the foredeck. This resulted in the foredeck and the side decks not being level. The difference was too much to sand out of the ply without a risk of going through the veneer. I had to level the 2 panels with a generous coat of epoxy. This shows as a darker patch on the deck. Not the end of the world but annoying nevertheless.

The next job was to fit the rubbing strip. This needs to be done before the angled deck panels are put on so that you can still clamp to the framing of the decks. I needed a lot of sash clamps for this. Fortunately my father in law has bequeathed a whole lot of them to me. I also had an extra long modern pistol grip style clamp which I was able to use clamping into the mast hole in the deck. I also used the rudder gudgeon with a screwdriver through it to clamp onto for the aft end. Clamping the whole 4m length without using screws takes a bit of ingenuity.

I trimmed the edge of my deck panels with light hardwood quadrant from the DIY store. This material used to be Ramin but now they don’t tell you what species it is. You could also use a dark hardwood as an alternative. The quadrant was glued into the gap between the ply panels and then sanded down level. The quadrant on the edge of the side bulkhead was glued on first before the angled deck panel. The angle of joints isn’t 90 degrees like the quadrant but I found it didn’t matter in practice.

The next process of fitting the little angled filler deck panels was a really tedious job. They have to be made oversize and gradually sanded down to fit exactly into the gap. The more patient you are the better the joints will be – but oh boy it takes ages. The rest of the build was pretty straightforward. Making the false floor took a surprisingly long time though as previously noted. Once the false floor was in the thwart could be fitted. The boat was now essentially complete. The long process of sanding and applying the finishing paint and varnish coats could commence. I put two coats of epoxy all over the boat and sanded down with 400 grade wet and dry used wet. It’s critical to get the boat completely dry before any further varnishing. There are a couple of patches on my boat on the false floor where the varnish went a little opaque due to some moisture. It’s also worth cleaning the epoxy with acetone of epoxy thinner before applying varnish as the epoxy has a waxy surface after it has cured. Virtually all of this is removed by the wet and dry but it’s worth going over the surface to make sure none is left. I used an epoxy paint for the hull so it’s not so much of an issue here.

Fitting Out

The trickiest job in fitting out is getting the mast step in the right place. I did it by putting the mast step in the boat loose and stepping the mast into it. I got the boat level with a spirit level on the gunwale and I then adjusted the mast until it was visually perfectly vertical. There is probably a more scientific way to do this but I couldn’t think of it. I then marked the position of the mast step and screwed it into the boat. The mast step has to be spot on or the mast will be way off vertical. Especially with a false floor boat the length of mast between the deck and the mast step is very short.

The mast has then to be cut to the right length for your boat. There is a guide to doing this on the SCOA website.

I bolted in my chain plates, rudder fittings and centre main U bolts. Long experience tells me to forget screws for these jobs. Basically I will only use screws where it’s impossible to get a nut on a bolt or where it’s a light duty. I installed access hatches in the right places so I could reach the nuts. In case of the rudder fittings as noted before they have to be attached before the aft deck goes on because the tank is too long to reach the nuts from the access hatch.

Overall the build took me about 3 months. Heaven knows how many hours I spent on it though. Some days I would do lots and then nothing much would get done for a week. Overall I really enjoyed building the boat and definitely want to build another one.

Measuring

If you have paid your building fee for the CD plans then you have also paid your measurement fee. You can take your pride and joy to your regional measurer and have it measured. Prepare to spend the whole day doing it though. It takes a long time to measure a wooden Streaker and you have to be there to help the Measurer do the measurements and turn the boat over etc. I only had one problem. I had misinterpreted the centreboard rules and my centreboard was out of class. The centre part of the board has to be flat. Obvious to old Streaker hands but actually the rules don’t explicitly say this. Fortunately 10 minutes with the belt sander and a fresh coat of epoxy sorted it out!

The result

I’ve really enjoyed the boat. Despite being quite a bit over minimum weight I’ve been very pleased with how competitive it is. On the plus side the boat is very solid and stiff and everything works the way it’s supposed to.

Next time

Inspired by the new short aft tank rule I’m now starting on my next build. This one is going to be down to weight. No doubt I’ll make different mistakes this time......