Running gear for a perkasa fast patrol boat

[dynamite25]

Last night i had a idea that i could use two thunder tiger car engines i already have one but need to buy another one they will have water cooled heads fitted to them instead of the car heads and use a three shoe clutch fitted to the thunder tiger engine, which will drive through the centre solid shaft from a buggy with a big spur gear which will be fitted on the end of the shaft which will turn two more spurgears which will be fitted to the propshaft, It's same as the set in an eb4 buggy but with two engines fitted a have put i pic of the engine i am gonna use on here and if use guy's could give me some feed back on this that would be great.

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[adzam]

teh set up sounds like a good idea, first of all, have you considered teh different rotaion of the engines ? , and secondly if fitting teh clutch assembly`s from cars, i would recomend some kind of elsectrically driven water pump ( car screen washer pump?) to keep water flowing around the heads if it`s at idle for any length of time , as heat will build up rapidly.

other tahn taht, sounds like a lot of work, but do-able.

 

[john]

teh set up sounds like a good idea' date=' first of all, have you considered [b']teh[/b] different rotaion of the engines ? , and secondly if fitting teh clutch assembly`s from cars, i would recomend some kind of elsectrically driven water pump ( car screen washer pump?) to keep water flowing around the heads if it`s at idle for any length of time , as heat will build up rapidly.other tahn taht, sounds like a lot of work, but do-able.

Adz what is is with words that have TH in them, is this a secret code :jeer:

 

[dynamite25]

yes i have thought about the rotation off the motors as you can get props for which ever rotation it goes so it can still go forward

 

[adzam]

it seems john i have probs typing certain words ,the,then and tehre.

odd just my typing

 

[dynamite25]

i've been looking at the way it would go in the boat so i'm gonna have just the one engine on the right side of the boats then the centre unit then a electric motor incase the engine stalls, i'm thinking of having the engine electric start to make easier to start up and i will use my chassis from my TT rallygame as a template to do the marking out of the mounting plate.

 

[adzam]

electric motor is a good idea mate, but electric start etc ( unless your using the same motor) weight is starting to increase. not too good if you want the boat to plane

 

[dynamite25]

The boat all this is going in is a 49 " precedent K D perkasa fast patrol boat the two electric motors are 540 s see attached pics of boat also the engine i am using is Thunder tiger pro 21 3.5cc 2.1 bhp 38,000 rpm.

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[duncan]

I think your figures are very wide of the mark. How much nitro to get these (unloaded?) figures? You will need a lot of water-cooling, not just the head, exhaust too. What method of electric start, battery,..... with glo to plug,another battery,more weight. Tuned pipe? I think a nice "cooking" .35 water-cooled boat engine would be cheaper, last longer, give no-hassle starting, reliable throttling, use less low or no nitro fuel. Your ideas are for a fast non-scale boat. You dont need speed in a scale boat like a Naval fast patrol boat. Just my humble opinion. Is there a model boat club near you where you can ask for advice?

 

[dynamite25]

I'm using that engine because i all ready have a spare one and those engines run really good and to make the engine watercooled i just need to change the head over to a watercooled head which will cost me about £15 the manifold will be watercooled aswell as the head,

i'm using a 540 motor as the electric start for the boat and the battery would be connected to the motor to start the engine then disconnected when the boat goes in the water and i will use a standard glow starter i you would start a model i/c car but i might not yet and a 380 for return to shore an that is if the engine should ever stall which it won't if i tune the engine right and the battery for this would stay in the boat,

There would be less weight doing it this way than if a put two electric 700 motors in it and the battery to power it plus the servo's and everthing else i would need, it will be two more months before i do anything to the boat i should have more info by then but thanks for your advice on this subject

 

[dynamite25]

I found all the specs of the engine i am using so the engine weight 390 g and two electric motors would nearly twice this weight plus the batterys weight aswell i would have more weight if i use two electric motors and batterys than if i used the engine and other things i will be using in the installation

PRO-21BXS Specifications

Displacement cc/cu.In 3.46/0.211

Bore (mm/in.) 16.6/0.654

Stroke (mm/in.) 16.0/0.630

Practical RPM 3000~38000

Output (BHP/RPM) 2.1/30000

Weight (oz.g) 13.76/390

i know this engine has alot more rpm and bhp than most marine engines but it's cheaper than buying another engine to put in, i have most of the thing i need i have the engine,fuel tank,controls,propeller, coupling,and all i have to get is the propshafts ,coolinghead,clutch,spurgears,rudders,and some other things i need so it is cheaper than fitting another engine in or fitting two electric motors in.

 

[andyc29]

twin prop rotation

Yes you can get left and right handed props but they must both rotate in opposite directions (usually center down the same appies for tri prop outer opp rotation center does not matter) or you will just go round in circles on the spot with the bow stayin still if you must power a boat with a glo engine make it a large single prop saves losing half engine power going through gearboxes i run a 1/24 scale wooden hull on 2, 12 pole electric golf caddy motors @30v and boy does it plane look for "perkasa handbrake" on youtube thats mine well up on the plane