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HINTS AND TIPS FOR PRESTWICH FSRV MULTI BOATS.

GENERAL .
On all boats it is very important to fit the propeller shaft straight with no offset angle. .
It is EXTREMELY important that the propeller shaft is fitted on the centre V of the boat. This is not exactly between the centre of the two rails. It is the lowest point of the boat and can easily be seen when looking from the front of the boat. When looking from the front of the boat with it the correct way up, the centre V will appear to be offset slightly to the left of the centre of the main rails. The rudder can be fitted in line with the shaft or it can be fitted exactly in the centre of the rails. When measuring from the transom, I consider the bottom corner of the transom to be the correct datum point.

Lightning 3.5cc geared. Balance point should be no more than 335mm from the transom without fuel in the main fuel tank. If the CG is too far forward the boat will never go fast. If its too far back it will be unstable.  The lightning is a very easy boat to get running correctly. Unlike the Storm the Lightning should no trimming adjustments.  Running with a cover over the engine will give good airflow over the boat with more speed and better stabilty. The nicad battery must be fitted as far to the left of the boat as possible. 200 to 300 grms of weight must be added to the left of the boat. This will vary according to many factors. Bigger props need more weight. This weight is ONLY there to counteract torque when the boat jumps from the water over waves. It will not affect the steering of the boat. DO NOT confuse normal hull trimming or turning with the addition or removal of the weight. Vary the forward or rearward position of this weight to get the correct balance point. REMEMBER .... adding a float chamber to the front of the boat with fuel inside, will move the balance point forward, and should be compensated for.
 The propshaft MUST be fitted on the centre V of the boat which is not exactly in the middle of the centre rails.
The Lightning turns best when a right side tab is mixed with the rudder.
Engine AS LOW as possible, propeller as close to the hull as possible . Recommended.... 18/35 gears and 1924 propeller or with a really powerful engine 18/34 gears with 1924 propeller.
Original ran with Prestwich pipe at 185mm from plug to end of front cone ( beginning of flat section). Weighed 3.5 kg without fuel.
Storm 3.5cc geared
Balance point should be no more than 340mm from the transom without fuel in the main fuel tank. The nicad battery must be fitted as far to the left of the boat as possible. 200 to 300 grms of weight must be added to the left of the boa
t. This will vary according to many factors. Bigger props need more weight. 

SPYDER2 7.5cc geared. Balance point should be no more than 375mm from the transom without fuel in the main fuel tank. 

Tornado 2000, Balance point 440mm from the transom without fuel in the main fuel tank. REMEMBER .... adding a float chamber to the front of the boat with fuel inside will move the balance point forward and should be compensated for .
Engine AS LOW as possible, propeller AS CLOSE to the hull as possible
Build the boat with 1mm clearance between prop and hull. The propeller may cut a little into the hull when running but that is OK. The propeller shaft should be fitted with zero offset angle. It should be fitted on the centre ‘V’ of the boat. NOT exactly between the centre rails. The centre V can easily be seen when looking from the front of the boat.
The Tornado should only be raced with the complete engine/tuned pipe cover. If the boat is raced without the cover over the engine, the aerodynamics are spoiled and the boat rides too high at the front making it unstable.
Using a carbon wing near the balance point, with some downforce is a good idea. The angle can be adjusted when first trying the boat. Set the angle so that the boat does not ‘ fly ‘ at the end of the straights.
On the left ( port) side of the boat, weight MUST be added. Between 350 to 450 grams is required. This will vary according to the propeller that is used. I use 4
50 grams with a 2127 propeller. This weight is to counteract torque, when the boat flies from the water over a small wave etc. It is NOT a compensation to help cornering or for normal running. The hull design will take care of that. The nicad battery must also be on the extreme left of the radio compartment.
The balance point without fuel on the original boat is 445 mm from the rear of the boat. With this balance point the boat will be a little front heavy at the start of the race. At the last half of the race it will be very stable at a time when other design boats are very unstable.
I recommend a central radio trim tab at least. On the original I ran with a starboard (rightside) tab too. On the Tornado, I do not mix the right side tab with the rudder.
The rudder is very sensitive on the Tornado. Very small movements are all that is needed. Use a 5 cell battery pack and at least a  7 kg/cm torque rudder servo. Adjust the rudder movement until the turning is not too sharp, then check for oversteering in the left corners. If the boat oversteers then cut a small amount from the rear of the rudder ( 2mm). Rudder shape will vary with propeller type.
Use 2127 or 2227 propeller.

Dave Marles. June 2002
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