Source:Kit: |
Possibly still made by
'Phoenix Model' - Norfolk Multi boat - 6.5cc or geared 3.5cc Glow engines |
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MY AIMS
MULTI RACING
These boats have very little draught in the water as the hull takes the form of a shallow vee hull and low deck to reduce wind resistance, they are thus sometimes referred to as 'flatties'. The aim of the hull design is to allow maximum straight line speed and 90o snap turns without slowing down. The boats race around a figure 'M' course in a clockwise or anticlockwise direction depending on where or when you race, this is a subject of constant debate. Currently Britain is running anticlockwise. Boats are classed according to their engine size,
A=3.5cc, You can use gearboxes, tuned pipes, throttle & mixture control etc. in fact anything you like as long as the engine size in within one of the classes. Tunnel boats and catamarans with trim control and surface drive should technically be the faster than multi boats but I haven't heard of anybody actually racing one in a multi race. Do you want to be the first?
Rule
for multi boat racing in the UK can be found on the MPBA web site. |
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SHG LASER I bought my Laser complete as a second hand sale from a model shop in Letchworth. It came fitted with a side exhaust HP40 motor, SHG quiet engine mount, ED MkII silenced tuned pipe, Accoms 2 channel radio and a ply boat stand. The engine and radio were tested in the shop so and it all worked so out came my battered wallet. The radio compartment lid is meant to be held down with Velcro but this made for a poor fitting and so was replaced with screws and new Perspex cover. The deck is curved around the radio box opening so a paper template was traced and cut out and transferred to the Perspex. The Perspex is then gently headed under the cooker grill until soft and placed on a curved surface and left to cool. Short lengths of steel wire were then brazed or silver soldered to 4 x 4BA screws, drilled holes in the top deck to take the screws pointing upward from under the deck, the lid is then locked down with nuts from the outside with washers but not with a torque wrench. A little cleaning, oiling and fuelling up and she was ready to go.
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ON TO THE WATER Turning abilities are very good on most multi boats, but my Laser lost a lot of speed when doing so. I was informed that the tuned pipe wasn't set up correctly by the original builder. I was also told that the engine was only a sports type and the tuned pipe should go under deck. This wasn't possible on my boat as it would have meant a complete rebuild of the boat, I wanted to start racing as soon as possible so the pipe stayed above deck. If you are going to build a multi boat the tuned pipe should be under the deck as much as possible to reduce wind resistance.
The boat also seemed to be ploughing it way through the water
and a lot of water was splashing up from the bows. I was told that
this was due to the hull not lifting itself out of the water high enough,
either because the centre of gravity was wrong, the engine was
not powerful enough or the hull had a
moulding fault. We put a steel ruler on the hull bottom, it
was a faulty moulding, it had a 3mm depression near the transom. The boat
was running fairly well so I didn't bother about the moulding fault as a
lot of work would be required to correct it. |
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THE TROUBLES START
Problem two was water getting into the radio box. All the time I had this boat I never found out how it was getting in. Even after a partial rebuild and a second total strip out in the radio box the problem still could not be cured. I couldn't stop the water getting in so I fitted a sump pump or auto bailer right into the bottom of the radio box! The boat now had two water intakes and two auto-bailers, two pick-ups for the cylinder head and manifold and two bailers for the flywheel sump and radio box area. I dread to think of all the drag this was generating. An auto-bailer is nice simple device to get the wet stuff out of your boat A.S.A.P. All it consists of is a water pick-up tube the wrong way around with a loop of pipe of tube down to an internal sump. The loop should be as high as possible (at least over the waterline) to prevent back siphoning when the boat stops. The onboard end of the bailer goes to the lowest part of the boat or where the water normally slops to when running. Another type of auto-bailer is a short ball valve, it is fitted sloping downwards and overboard in the lowest point in the transom. When the boat is moving forwards the ball falls backwards and rests against a mess so allowing water in the boat to flow out. When the boat stops, the ball floats back up the tube and seals itself against an 'O' ring. If you use one of these bailers, regularly wash them out because if rubbish gets in and gets between the ball and the ring, your boat will start to sink.
Siphon Type Auto-bailer When I bought this boat, it was fitted with a small clunk type fuel tank which was removed and replaced with a much larger Perspex tank made for me by a friend Brian who works in at a sign writers. The fuel soon got the better of the glue and the Perspex didn't like it either and buckled it up when emptied, don't ask me why! Two black SLEC tanks were then fitted and linked together to feed each other as the fuel level drops.
Problem three developed with the throttle to servo link became very sloppy. When I first bought the boat the link between the radio box was a straight wire link with the servo arm through a hole in the bulkhead and onto the throttle. A long link that could easily be kinked or bent. I fitted an all plastic snake link but had difficulties in making the ends fast. The ends were clamped down but the clamps and bends caused a lot of friction and made it hard for the servo to drive the snake which also led to slow and unreliable control. After a short while I removed the snake and fitted two straight heavy gauge piano wire links and a Robart square water tight fitting in the radio bulkhead. This link was much better and never gave any trouble. Use heavy gauge piano wire for radio links and use adjustable metal clevises, but don't make metal to metal joints as you may get radio interference.
With all of these problems overcome I was at last ready for my first race. |
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THE BIG RACE
A few
seconds to go, radio on? Check. ..."Come on start you stupid thing, START!
Ten
feet on the water BANG, she stopped dead?!??! |
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Back home I reviewed the situation carefully. Unfortunately fast multi boats cost money and I was going to have to spend some more on my boat to become competitive. By means of a friend of a friend, an OS 40FSR racing engine became available at a reasonable price. It's an unusual type of engine as it has a 'Dykes' piston ring of an 'L' shaped cross section. The engine has a front rotary inlet valve and carburettor. In went the new engine and reshaped throttle link and she was ready for the water.
Now she
really was moving, or so I thought, anyway she was fast enough for me.
It did a submarine act once but I put this down to a freak wave...I
hope. After a short run in period for the new engine and I was ready for
my next race. |
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THE SECOND BIG RACE First lap. Boat over revving badly, the prop was too small. Brought her in, larger one fitted and off again. Second lap. Engine over loaded. Brought her in, finer pitch propeller fitted and off again. Third lap, OK.
Fourth lap, burnt out the silicon tube
joining the manifold to the pipe. Eighth lap, "What's that knocking noise?" The leading boat laps me in less than two of my laps. Tenth lap. "That noise is getting quite loud now". Twelfth lap. Very noticeable loss of power but still going. Lead boat now lapping me in one of my laps. Better bring her in to have a look.....ten minuets later I have an engine striped down over the jetty and I'm looking at a split ball race cage and a shot Dykes ring. All in all, a good days racing!! I get out my 'Little pig' for a run after the race and pretend I can my take my failure like a man. When I tried to find spares for the new engine, I realised why it had been sold to me so cheaply, there are no spares for them. A model shop in Hadleigh near Southend-on-sea 'knew a man that can' and I put the engine in for repair at a very reasonable cost, much to my delight. While waiting for the engine to be returned, I had refitted the original HP40, I had made the new engine fit the old mount so that both were interchangeable. The boat
was now back to it's old slow and reliable self with everything passing
it within two laps. Ian in the local model boat club, the club had a same
laser hull as mine and told me to modify the rear of the hull as the
moulding fault on my hull was really bad. A large tin of Isopon
(car body filer), a lot of filing and sanding later and I was ready to try the boat
again. My LASER was now
running much better, the bow was now lifting right out the water and
the hull was cutting a clean line in the water. Now it took at least four laps
before anyone was lapping me!!! I went home quite pleased with my efforts
and put the boat up for sale! |
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CONCLUSIONS and LESSONS
Many modellers have taken up the challenge to race a multi boat as fast as possible and have great fun while doing so. A newcomer can get into multi racing quite cheaply by buying a second hand boat or by building your own boat without buying the most expensive racing available. What hull, engine and hardware to buy is a difficult choice but you'll find NO END of advice on the subject from fellow modellers. But a note to all racers, 'race with a smile!" I've noticed some people can get very upset and bitter if they loose. Remember... they are only toy boats no matter how much you spend on them! I'm off now to find a concrete bunker to hide in... Well all of this is just my opinion, but what do I know! |
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NEXT
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FINAL SPECIFICATION for LASER HP40 glow
engine |
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MODIFICATIONS Hull needs modification Metal propellers. |
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PERSONAL RATINGS
Value ....................
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(out of 10) 3 (My hull was concave at rear) 3 (Hull is old design) 3 (Radio box opening small and lid is poor) (Can't comment, didn't buy from new) 1 (All multi boats look the same) 2 (Hull rides very low) |
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