Laser    By   SHG Marine



Possibly still made by 'Phoenix Model' - Norfolk
Multi boat -  6.5cc or geared 3.5cc Glow engines



To run a racing 'Multi' boat and win a race or two......

Most   model   boat  racing in this country is done  with   multi   boats.   Multi   stands  for multiple as in multiples of boats running together  at   the  same  time.  In the old days when radio controlled channels were  far   and few between,  boats were raced one at a time against the clock.  Multi   boats  are  built for out-&-out speed,  cornering and  reliability,  other  factors   such  as appearance and innovation don't come into the equation.

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, 

B= 6.5cc 

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.

All  multi hulls are made from fibreglass. When buying a hull take along a  steel  12"  ruler to check the hull for flatness especially near the transom. If  the boat does have a hollow, the boat will never run to it's full potential.  You  now  have two choices, 
1) but the boat and fill the hollow with  car  body filler or
2) buy a better boat.
I recommend the latter because if there  is a fault here how good will the rest of the boat be?

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. 


The   boys at the local power boat club showed me how to run one of  these  babies.   After it had been tested they handed over the controls to me and  I run  the boat up the lake very gingerly,  it was much faster than my SHG  SHADOW   and it felt more powerful too.   I then attempted to bring her in, unfortunately the lake was flooded at the time  and  the  water was up over the jetty.  I slowed the boat down but misjudged the speed.  The boat  crashed   into  the  front of the landing stage and flipped up on top  and  skidded   across   the   surface and came to a halt with  a  bent  rudder and smashed propeller.   "Well  that's  one  way  of  stopping it."   I was  told,   "But  there  are  better ways!"   I put down  the  transmitter,   tried to  stop  shaking  and  picked  up the boat.  A few minutes  with  hammer  and pliers soon  straightened  out the rudder and also replaced the  propeller, refuelled and was ready to try again. A  few more runs during the day and I saw I didn't have a very  fast  boat   but  at least I could enter a multi race.  

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. 

After a few  weeks  running the first thing to go wrong was the aluminium manifold,   it broke  in half.   I made one up by brazing copper pipe and fittings together  but  this burnt out within a two runs.   A better one was made from bent copper   pipe  brazed onto a brass plate which lasted until the boat was eventually sold on. 

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

Ball valve Type Autobailer

  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.


 The  warming up laps were good.  My boat wasn't very fast so driving skill  was going  to come in handy. I considered my race tactics, I would have to  give way a lot as I knew I had the slowest boat on the water.  I could try  ramming  all  the  opposition  as  they  lapped  me  but  this  might   be  considered a little unsports-man-like.   I brought the boat in,  refuelled  and was ready to go.  A few last minute bits of advice was now coming from  the other club members,..  "Don't come near me if you know what's good for  you." 
"You're dead meat." 
"Call that a multi boat?"
etc.   but I took it  all in the good spirit intended!

A few seconds to go,   radio on?  Check.
Wait for it .... 
.......wait for it ...  

 ..."Come  on start you stupid thing, START!
 ....  Come on,  you  was  just  running  a second ago,...  
                    Ahh!  At last!,.. 
Throw  her  in  And  WE'RE  OFF!........"

Ten feet on the water BANG,  she stopped dead?!??!
"Watch out for that  piece   of  wood  in  the  home straight!"  someone calls  a  few  seconds  later. 
"@$%^*&%#*(+:><?!!"   I muttered to myself as everyone shot off round the  course and completed the race.

 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. 

"Fuel? Check. Radio? Check.  Glow?  Check.  Water?  Clear!"  Ready.....GO!  A good start this time.

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. 
Brought it in and replaced   the  silicon.  

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!

If  someone  that obviously knows what they are talking about  tells   you  could have bought a better boat, listen to them. Especially if he can tell  you  why,  if   two  people  tell you the same thing put the boat  up  for  sale   and  keep  quiet.   This is an old hull now and many hulls are much  better suited  to  racing.  If you see one for sail, (get it?) it will run  quite  well  with  a  gear  box and / or a very 'hot'  engine and  if  you  modify  the   rear   spray   rails to eliminate  the  slight  chamber  and  increase  lift. 

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! 

 NEXT ....
Having decided that I don't really like multi boats,   it was sold after a   few  months  of sitting on the retirement shelf.   I decided to  stick  to  boats  that  look  more like the real thing.   I next wanted to  build  an  electric   boat   again  but  one faster than the  PIRANHA.   I  had  read  somewhere   that  surface  drive  make boats faster so I looked for a  kit  that  had   one.   I  came across the Graupner HYDROSPEED.  I bought  one,  took  it  home  and told  the wife I had striped down the  Piranha  for  a  rebuild  and  the  boat   would   look completely  different  when  I  was  finished.   I  was shortly sussed  out  when she saw only one boat in  two  different places.


HP40 glow engine
SHG Quiet Engine mount
45X propeller
EMC rubber coupling
ED Mk II tuned pipe
2x black SLEC fuel tanks linked, pressurised
Modified hull
Accoms 2 channel radio

Hull needs modification
Metal propellers.

Value ....................  
Kit Quality ..............
Kit Design ...............
Ease of Building .........
Finished appearance ......
Handling .................

(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)



From left to right & Top to Bottom.
SHG Laser   -   SHG Shadow
Hydrafibe PREDATOR   -   Graupner Arrow
Krick Avanti   -   MFA Piranha   -   Graupner Hydrospeed