Christina 25 offshore powerboat

[Guest]

I am making a powerboat loosely based on the Fairey Christina 25 Powerboat based on Thunderbolt.

I was going to have 2 electric motors powering it like the real thing (real one was twin V8's) but was then decided that 2 24v motors & the battery pack to power them would be very heavy So i recently decided upon a single 2.5cc nitro engine

I dont have any pics of the boat yet or the parts to finish off the hull but i have a pic of the engine & 1 of the 2 24v electric Navy Compact motors it was going to have. that now cost £31.95 each (I got them when they were £25ish each)

They are listed as 6-9.6v but on a 9v battery they are slow & the battery went hot & died in about 5 mins.

The boat has a Heavy Duty prop shaft i think is 230mm long & M4 threadded

The engine cost me £50 & has not been run but i think it has a problem. When turning it over their are bubbles between the piston & the cylinder sleeve when the piston goes up & it bubbles from between the block, piston & sleeve when the piston goes down so i think i might have a compression failure at some point in the future but it will be funny to see but annoying to repair.

I have to somehow make a clutch bell or make something to fit on the clutch bell to connect it to the splined nut that goes onto the UCJ for the prop shaft.

I will have to make a custom exhaust & it will NOT have a silencer! & it will be a rather large boar because it lowers the pitch of the engine alot.

I was thinking of making a cover to fit over the air cooled head that would draw water up from under the boat, through the head & out of the exhaust using the exhaust to draw the water through like a vacuum but i think to be more reliable i should get the fan from a computer & use that for cooling since i made the cabin with an air scoop up both sides that were made to have pipes from them into the electric motors & then back out at 1 side.

I don't really have a clue about powerboats but i do know more about narrowboats & tugs ( I have a steam tug in the making also but having trouble finding a decent Mamod te1 boiler for it)

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[Guest]

Hers is what i have so far £62 worh of electric motors, £50 nitro engine & about £20 worth of wood & other crap.

My hull is longer & straighter than the Christina but everything on it is similar to that of the real thing.

I m going to remake all the deck(i think) & the cabin because they are balsa wood & although it is lite witch is what i want but its weak witch isn't what i want.

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[HAWKERHUNTER]

Hi Adam. I would have stuck with the electric motors. They are a lot less bother than nitro. Getting set up with the electric can be expensive but once you have the right charger and batteries you would be ok. You will need to make sure that you secure and reinforce the area around the nitro engine because you will probably put a lot of force on the hull when you try and start it even if you use an electric starter. I know a bit about nitro engines so if you can be more precise about where you are getting air bubbles I may be able to help.

Steve