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FSRV BOAT HINTS AND TIPS

SIGMA 51 for 25cc gas engines

Sparkplug to transom with Zenoah should be close to 540mm (transom is the vertical part of the back of the boat).
CG without fuel 460mm. Fuel tank is between engine and radio box.
CG and strut height can vary with propeller size.. For example on the prototype with 7016/2 the strut is as low as possible and parallel, with 7015/3 the strut centre is higher at 13mm from the tip of the V and has approx 2 degrees negative.

Dimension A . As low as possible.

Dimension B Tube is offset 2 to 3mm to the right of centre. (starboard)

Sparkplug to transom with Zenoah should be close to 540mm (transom is the vertical part of the back of the boat). Fit the engine to the complete rubber mount assembly and position it where shown but do not fix in place yet. Fit the coupling to the motor. The Strut MUST be fitted at the position shown in the top right drawing. Check the drawing above for the position of the tube through the transom. Using Zenoah engines the propshaft should be offset to the right(starboard) by 2 to 3mm as shown on the drawing. DO NOT use an angled strut or angle the strut with packing under the brackets. It should be parallel to the keel when looking from underneath the boat. Drill an oversize hole for the proptube in the ‘V’ of the transom which is elongated vertically to enable you to raise or lower the strut. Many racers would leave this hole open for future adjustments but some would seal it with silicone glue after finding the optimum setting for strut position. Cut the prop tube to length so that it is about 10 to 15mm from the coupling but pushed into the strut as far as possible. The tube should run along the bottom of the hull from the transom and then be curved upward to slide into the coupling. The tube should slide inside a piece of the next size bigger tube ( KS 11/32) of a length of around 100mm. This short tube should be epoxied to the hull after the tube is lined up so that the centre of this tube is approx 250mm from the transom. The front end of the tube near the engine must be supported. The tube should only be fixed at these 2 points . i.e. Do not fix it near the transom or it will be impossible to adjust the strut height or angle. A T-bar can be used or a piece of carbon sheet or 6mm plywood can be slid over the front of the tube and it must be epoxied in place. Cut the flexi to length, remembering to leave a gap of 5 to 6mm (not less than 5mm) between thrust washer and the strut. Do not cut the flexi too short, because it has to go inside the coupling as far as possible. The collet in the coupling may be closed up, if so then open each slit with a knife blade or something similar. When the collet coupling is tightened onto the shaft, use a lot of force. The fuel tank must be fitted behind and to the right side the engine, i.e between engine and radio box. Sport users can attach the the tank to the inside of the or use your favourite method. Racers will have their own ideas but keep the tank as far back as possible in the boat.The flexi should slide smoothly into the coupling, to be sure of correct alignment. Fix the mounting feet in position with fibreglass paste. This can be reinforced with fibreglass mat or tape if required. The inside of the deck hatch opening at the front of the deck should be cut back until the hatch fits into it. Fix the hatch down using GA8 hatch fasteners or similar at the rear. At the front of the hatch, trim the projecting part so that it slides easily under the deck. This part may need reinforcing with glass cloth and epoxy. The radio box can be fibreglassed in place or fixed to the rails with brackets. Take care to seal any holes in the radio box with cyano, epoxy or silicone (preferably cyano or epoxy). A standard size metal geared high torque rudder servo of at least 9kg but preferably 13 kg torque should be fitted on its side on a strong servo mount of aluminium or carbon angle. The throttle servo can be any standard or high speed standard size or small size. Use a 5 cell Nimh or nicad pack for the receiver.

Turn fins should be fitted at 90 degrees to the hull bottom on each side as close to the outside edge as possible. Make sure the brackets and turn fin are very strong. Movement in this area will affect the turning of the hull.
Trim tabs should not be necessary. Trim tabs will slow down any boat. The trim of the hull can be altered by strut height or angle and rudder position. The boat will be fastest with a strut but if a stinger is used it is recommended not to use the larger stingers such as Top Secret.

The flexi shaft MUST be removed and greased after every days running. Mercury Quicksilver grease is popular but any grease is sufficient.

Only use balanced / sharpened propellers. Using the CS23A long tuned pipe and 100 degree manifold and fix the rear of the tuned pipe with a stainless hose clip and aluminium bracket. Pipe length from exhaust flange on the engine to widest part of tuned pipe should be 330 to 345mm. Start at 345mm and shorten to get more rpm.

Take care to range check the radio before use.

For Zenoahs and other petrol engines use 1/4" flexi with 1/4" stubshaft. With the kit supplied prop the boat will be capable of 55 to 57 mph. For highest speed buy one of our special modded propshop props. To attain the highest speeds will take some time in adjustment of strut or stinger height and angle. If you are racing the boat then keep checking this website page as I will be producing additional or replacement items to aid boat stability and speed and will provide full trimming and running instructions.

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WE SHIP WORLDWIDE email here Phone. UK 07842 634090 international 00447842 634090. PMB, Mill St, Golborne, Warrington, WA3 3QJ. England.. Model boats of all types including FSRV, FSRH, FSRO Offshore, Deepvee, fast electric, cats, zenoah gas boats.