Viper Speedboat  
By Andy McGarrity - Great Britain

The idea

In mid-March 2006, I came up with the idea for my new project, but at first it was only going to be a model boat, not a full size one! It was to be based loosely on the lines of a Lesro Javelin (Photo 1), a model that has been around for many years and still looks good. I was going to do my own version of it, using one side-on photo that I scanned from an advert and the length and beam measurement from the specifications. It was going to be 38-1/2 by 11 inches with all other dimensions worked out roughly from the photo.

click to enlarge

Photo 1

I didn't know draught or hull shape below the water and I was just starting to work on this area when my friend suggested doing one to sit in! He offered temporary use of a Honda 8 HP generator engine if I wanted to build a full size one (Photo 2). After a bit of computer magic on Photoshop, I ended up with a photo of my head on the model at the scale I would have to make it for me to fit inside, this resulted in a 9ft boat roughly 32 inch beam. It looked good (Photo 3).

Photo 2

click to enlarge

click to enlarge

Photo 3

The main problem with my idea appeared when I managed to track down a different photo of the Lesro Javelin, stuck my head on it and it looked a bit too narrow beam for where the centre of gravity was going to be with me and the engine in it (Photo 4). My friend appeared at this time and said: "I thought you were doing it for two people,anyway" This is where the boat started to diverge from the Javelin.

Photo 4

click to enlarge

After some measuring and mock ups with bits of ply to simulate widths required for seating, I worked out that I could fit two people and keep the deck/cockpit side proportions if I made it 46 inches wide. I was still keeping to the 9 foot length as I had a mock-up photo of it already. I priced 10 ft sheets and decided to cut £200 off my boat! I changed the length to 7 foot four to get the sides from an 8 ft sheet of ply. This adjustment required another Photoshop job, shortening the length, but keeping the height resulted in something that looked possible at reasonable cost (Photo 5).

click to enlarge

Photo 5

The plan

The plan started life on Photoshop (again). Using the side photo, cropped to length of the boat, I resized the image to make a 22 inch (1/4 scale) photo which I printed on three sheets and taped together. I still didn't know any of the 'underwater' measurements, so I took my first try at weight estimation to see what sort of volume I would need below the waterline and came up with 8 inch deep 'V', which was marked onto the photo and the missing curve added to meet the bow. I traced the photo and started adding details until I had enough information to work out bulkheads etc.

At this stage I joined 6 bits of card and started on my full-size drawing, using the same type of slotted together construction as my micro yacht used. I decided to use 3 laminations of 3/4 ply for the backbone (I don't know if that's correct term!) with a mixture of 3/4 and 1/2 ply bulkheads.

My steering was to be based on a gearbox from a dead angle grinder, so suitable mounting was designed in by using two ply braces spaced the width of the gearbox apart and extending forwards to form the centre piece between the dummy vents, which were going to be used for ventilation but ended up mainly for looks. I may try lights in them. I think the vents look better than the flat panel that the Javelin has. The braces, bulkheads and backbone are all slotted to key into each other, making it hard to go out of alignment.

With most of my plan decided and drawn on the giant carboard, I started to cut bits of ply. I must say at this point, that the planning stage keeps going until the boat is finished; particularly the order of building. It is easy to get carried away and make things difficult for yourself, like gluing on the bulkheads before you have drilled the holes for the steering and throttle, still possible, but not as easy or neat as it could have been. Yes, I did that! There were a few small things that could have went pear shaped, I was routing a part and the cutter bearing collapsed, allowing the cutter to decide it's own path through my nearly finished bit of wood, luckily it is an 'out of sight' piece, so I left it as a 'feature'! Another close call came when I was cutting out the transom, the ply I was using was actually swapped for a model plane airframe. The friend I got the wood from had drawn parts for his own version of the yacht I built, but gave up. The problem happened when I started following his line with the jigsaw! I realised within 1/4 inch so it was not a disaster.

The dry build

Starting with the backbone centre lamination, I then cut my master bulkhead which would be used as a template to router flush all the bulkheads of the same lower section. There are 5 which are the same but have the tops trimmed after routing. Then the template is trimmed to fit in its final position. I made the other bulkheads with each edge angled to fit skin curve at that point, to cut down on sanding. My angles were pretty close, but there was a LOT of sanding later to get framework pieces ready for eventual 'skinning'. No glue was used at this stage and I was able to dismantle the parts and put them in my 8x4 shed after I had finished for the day.

I made up more braces to hold the top edges of the front bulkheads in place and side rails for the rear/midsection along with the rear portion of the cabin/cockpit sides which braced the cockpit and engine bay areas together. I added doublers to the backbone and adjusted the bulkhead slots to final size and was now able to pick up the framework, still with no glue! (Photo 6 and 7) I added more bits and worked out cable runs for steering and throttle etc.

click to enlarge
Photo 6

click to enlarge
Photo 7

Now was the time to think hard about the engine arrangements! What I had originally planned with 8HP Honda motor never happened due to my engineering friend getting busy at work again! I had designed the transom to take an outboard or an outdrive unit that would fit over the transom and I even had a lot of the parts (Subaru cam belt and pulley, chain and sprockets etc), but no cash to buy the square section steel tube for the 'leg'.

My neighbour sold me a longshaft Seagull outboard (non runner) for £40 (Photo 8), which I was going to use for testing until we eventually made the outdrive. A night's work had it running and cleaned up a bit. Repainting the tank finished the restoration. Next morning, I fired it up to let him hear it. He looked as if he wished he hadn't sold it!

Photo 8

click to enlarge

Still keeping my hopes up, I designed the mountings, throttle and steering to take an inboard motor in case it ever happens! The transom and engine mounting plate are laminated ply 2 inches thick and are locked together with the backbone and bulkheads (Photo 9). It is very solid and that's before any glue goes near it. The glue stage was approaching, there wasn't much more I could do until I glued at least some of my 'kit' together. The trouble was I didn't have a big enough shed to build it in. A 2.4 metre square gazebo was fixed to the side of my shed, I added tarpaulin sides and a portable CD player and I was ready to glue!

click to enlarge

Photo 9

The Build

I started gluing the bulkheads on one at a time, using the other bulkheads and braces to hold it until glue set, then I removed braces etc. and glued in the next bulkhead and braced it up again. It seems like a long process, but it ensures that everything stays where it is supposed to. When all the bulkheads were fitted, I glued in the braces, added gussets and ended up with a rigid framework to fit my stringers (chines?) to. These were steamed using a wallpaper stripper and a chamber made from 3x3 and a large plank laid over the top. I clamped them to the boat with no glue and let them set in that shape. This was not as effective as I thought it would be, and instead of a 23 inch curve it sprang back to about 3 inch curve. I cut notches in the bulkheads to accept the stringers then glued them in place, added gussets and could now see some very nice lines appearing on my frame (Photos 10 and 11).

Photo 10

click to enlarge

click to enlarge

Photo 11

I fitted the deck first, then bottom skins (Photo 12) to give me access through the sides for varnishing and to the underside of the steering area (Photo 13). I left the sides off until the last moment, varnishing all the bits that would be hard to get to later. I fitted the steering and throttle to make sure it all worked, then removed it and glued the sides on - sounds easy.

Photo 12

click to enlarge

click to enlarge

Photo 13

Glueing the sides on required 2 very late nights to give me a chance to get the glue onto the frame and the side clamped on before the glue dried. Mid-day in summer gives about 4 minutes to get this done. Clamping was the hardest part as I was running out of things to clamp to and I did not want to use any screws (Photo 14 and 15). I eventually managed it and after trimming off the excess, I could see a solid version of my idea.

click to enlarge
Photo 14

click to enlarge
Photo 15

I was worried about water getting on my raw wood, and the boat had it's own brand new tarpaulin, which was lucky, as a nights worth of Scottish rain had broken the peak of the gazebo which filled up like a pond and was hovering over my boat with about 20 gallons of water straining the fabric and dripping everywhere. I managed to soak myself but the boat stayed dry. The poly-shelter was repaired and re-taped to keep the midgies and moths away from my varnish and I spent a couple of weeks varnishing!

Varnishing and Painting

This deserves a section to itself as it is a critical and major part of the build, requiring quite a lot of time to be spent inside it, upside down with my legs resting on the back of the seat, while trying not to sweat on my new varnish! All parts, inside and out, have at least 4 coats of varnish (Photo 16 and 17). I know a lot of people go for more, but I was on a limited budget!. I had decided to see how it looked with just varnish before venturing onto painting. I had drawn an artists impression of it (Photo 18), scanned it into the PC and printed off a bunch to let me colour in a few different schemes, so I knew roughly what paint scheme I was going to do if the varnishing didn't look that good.

Photo 16

click to enlarge

click to enlarge

Photo 17

Photo 18

click to enlarge

Due to using different woods, glue lines etc, I didn't like the varnished only look and decided to paint it yellow using 2 layers undercoat and 5 enamel topcoat (Photo 19). I was going to do just three topcoats, but after finishing my first tin of yellow, halfway through the third coat, I opened my 2nd tin and started rolling it on, then noticed it was a different shade of yellow! I had not checked the batch number. I had to finish that coat and do another 2 coats before the original shade was hidden. I will check batch numbers next time! The bottom of the hull got 5 layers varnish, 2 undercoat and 3 black gloss enamel (Photo 20).

click to enlarge

Photo 19

Photo 20

click to enlarge


Steering is by ropes running around home made ply pulleys which have mitre saw guides as pulley shafts and tubing from a baby bouncer as bearings, onto a drum attached to the angle grinder gearbox (Photo 21), with a laminated ply steering wheel (Photo 22) which uses a Nescafe coffee jar lid for it's centre and another to cover the steering bearing (I like re-cycling)(Photo 23).

click to enlarge

Photo 21

Photo 22

click to enlarge

click to enlarge

Photo 23

The tiller arm of the outboard points down into the area that was going to be the engine bay and has the steering ropes attatched to the end of it. This led to the hatch being different to the one in my artists impression. Throttle is from bicycle gear lever and cables (Photo 24).

Photo 24

click to enlarge

I forgot to mention that my daughter's outgrown wooden bed was used extensively during the build. The head and footboards supplied large pieces of wood for the transom, seat back reinforcement, and numerous other bits. The lower slats from the bed were very useful for clamping the outer skins to my framework..

There are a total of 198 wooden parts in my boat. Some parts could have been made in one piece but would have required more full sheets of ply, which I didn't have. The windscreen was made from a piece of perspex that my friend offered me. It is as large as I could manage from the oddly-shaped bit. The chrome bits came from a light fitting reflector. Rubber edging was in deep storage for twenty years before finding a home! Upholstery was made from a cowskin that someone gave me years and years ago. All hand stitched by myself, it was a pleasant break from sanding and varnishing and has ended up being quite comfy as well!(Photo 25)

click to enlarge

Photo 25


This is the bit that keeps you going to the end of the project and it had arrived (Photo 26) about four months after starting to cut my parts. The boat was placed on the construction stand that I made from 6x2 timbers and 3/4 ply end plates. The boat and stand were lifted onto a motorcycle trailer and ratchet strapped down. During transportation the stand collapsed a bit and I thought my creation was going to end up sliding down the road at 50mph! It didn't.

Photo 26

click to enlarge

We got to Loch Lomond and registered for a year's use of the Loch for £5! The boat was lifted into the water, Seagull outboard attatched and I got in for the maiden voyage. I managed two pulls on the starter cord before I was blown back towards the beach, a good push by a friend and I was able to give it another try and it started! I wasn't exactly skimming over the waves so I tried full throttle but discovered that it was at full throttle already. Any thoughts of calling it a speedboat would have to go on hold for a while!

I did have fun, but would have liked a bit more speed.It felt stable in the water and coped with quite large waves, well, they seemed large from where I was sitting. I cruised about for about 5 minutes by myself then went in to pick up my friend. Having the extra weight aboard did not seem to affect the speed noticeably, so we ventured out a bit further into even bigger waves, glad that the dummy vents on the front were still watertight! The maiden voyage went without any problems apart from lack of speed(Photo 27).

click to enlarge

Photo 27

I must say that I enjoyed the entire project (Photos 28 and 29), with varnishing maybe a bit less enjoyable than sawing and gluing. It has ended up a bit heavier than my estimate but I reckon it's tough enough to go through a Jetski! Not easy with a Seagull engine! That was about to change!!!!

Photo 28

click to enlarge

click to enlarge

Photo 29

Someone's Trash

A strange thing happened when I was going to visit my wife in hospital after a scheduled operation. I got a phone call from a friend who was dumping rubbish at the local waste depot. He wanted to know if I wanted an outboard engine that was being dumped. "What size", I said, "9.9" came the reply. I said that I would take it. He said: "do you want another one that's here, it says 9.9 as well?" I told him to guard them till I got back from the hospital and picked them up.

Two Evinrude 9.9 HP, one short shaft (1986) and siezed solid and the other a longshaft (1983), which turned over, but had been ripped forcibly from it's mount,putting a 'Z' bend in the gearchange shaft and wrecking the casing in a few places. Both were covered, and as I later found out, filled with what I call seacrust. I could not see the thermostat when I took the cylinger head off.

A month or so of cleaning, swapping and painting parts has brought the motor to the stage it is at now, about a 50/50 mix of the two motors and requiring 2 seals, a circlip and one mounting bolt. I have just ordered these parts, but due to having parts of 2 engines, I have to try and explain why I need 3 parts for an '83 motor and one part for an '86 motor. It did need rubber mounts but I managed a very good refurbishment with a scrap of denim and some superglue! Don't laugh, I saved about £50 by repairing them.

I also need 2 sheared bolts removed, which my engineering friend assured me he would find time to do! I need to wait until it is all back together before I find out if it is going to run. One set of electrics was corroded very badly. Luckily it was from the siezed motor. The motor cover was going to be sprayed yellow, but I decided to cover it with heatshrink covering for model aircraft, using a surface primer to etch the plastic before carefully ironing it on. I must admit that I have built and covered about 90 planes with this type of stuff, so I am quite good at it. It is very easy to end up with a lot of air bubbles or creases.

I then cut the Evinrude lettering from black Fablon. I think it looks pretty good compared to how it looked when I got it (them). The photos don't really show how bad they were. Before (Photo 30 and 31) and after (Photos 32 and 33).

click to enlarge
Photo 30

click to enlarge
Photo 31

click to enlarge
Photo 32

click to enlarge
Photo 33

I mounted the empty casing on the boat for the photo (Photo 34) but I will have to wait for my spares before I can go further. I still have to make up a bracket for my steering to attach to and fit my throttle cable to the carb, but I will probably leave these jobs until I hear it running. Hopefully it will run and my 'boat' will become a Speedboat. I haven't seen many boats of this size, so I don't know what to expect from 9.9HP. I was a bit worried about 'copying' the Javelin, but I think there are enough differences to call it my own design ,it is shorter, wider, has nice vents, different windscreen, is outboard powered and most of all, it's full size and a two seater! Hope you like it. Andy. PS. You can never have too many clamps!

Photo 34

click to enlarge