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[strokkur]

Hi All

I've been lurking on here for a few months and have finally got round to posting about my Model Slipway Vosper RTTL.

Really want to say thanks for all your help with my build (you didn't know you were helping me but even my choice of kit was as a result of reading this forum) I've learnt loads. 

I live in Blackpool (Bispham) so I'm aiming to pop over to Fleetwood once it's ready as I believe the lakes there are open to the public (does someone on here know if that's true?).

Anyway here are a couple of pics as I'm nearly ready to start painting (got an airbrush for Christmas and dying to use it for real):





Cheers, Sam

[Perkasaman2]

Hello and welcome Stokkur the vosper RTTL is a real favourite on here. Good luck with the painting. 

[strokkur]

Hi all

I popped to Fleetwood this evening to try out my Model Slipway RTTL (still got a couple of detail items to add but couldn't wait any more). There was nobody else there so kept my fingers crossed I didnt get stranded in the middle. Everything went fine, bow lifted nicely and she bounced through the choppy water very nicely. Steering was good at speed, not so great going slowly.

All in all I was dead chuffed with my first attempt.

There were a couple of things I'd like some help on though....

I got about 20-25 minutes I think by which time there was noticeable slowing. Also on checking the motor (a Speed 400) it was too hot to touch. Not sure if it just needs cooling or I should change something. Just using the prop that came with it albeit on a 2mm shaft as I trod on and bent the supplied one!

Battery pack is a 6 C cell nimh pack rated at 3000 mAh if I can sort out the motor heating up would like to get a longer run time somehow as well.

I couldn't take a picture as I couldnt juggle camera and radio at the same time.

[Brian Roberts]

Hi Sam

If you fit a water scoop behind the prop, then plastic tubing to a cooling coil around the motor and then more tubing to let the water exit on one side of the boat. That will definitely keep the motor cooler.
Are you sure it's the right size prop for the job? If it's too big the motor will struggle and overheat.

Brian

[strokkur]

Hi Brian

Thanks for the idea re water-cooling - It would mean some hacking about to get the change the motor mount, but is probably do-able and I may decide to go that way. This is my first boat and was intended as a learning exercise so if I'm going to try things like that out this is the boat to do it first.

I was also wondering whether it's possible to fit a heatsink - same sort of thing fitted to the cpu in a PC to the top of the motor and whether anybody knew where I could get one.

The prop is a plastic 35mm 3 blade supplied with the kit and the motor is a speed 400 also supplied with the kit, don't know whether thats a good combination?

Cheers, Sam

[Brian Roberts]

Hi Sam

Not sure that a heat sink would be any good in this situation, also the props are quite small so I don't think they're a problem.

So I think we're back to water cooling..........!

Brian

[strokkur]

Well that's ok - I'll have a bash. Is it simply tubing or do I need a pump or something?

Also the lake is salt-water is that going to be a problem?

Cheers, Sam

[Brian Roberts]

Hi Sam

Just simple tubing, no pump necessary because the water will be forced through the coils by the action of the props on the scoop.

Salt water shouldn't be a problem, just make sure the system is flushed out with fresh water after each session.

Brian

[malcolmfrary]

Swap the prop for something a bit smaller and with 2 blades to let the motor spin up more easily.  If you look at real launches, the props tend to look ridiculously small.  The smaller, faster spinning prop will shove water back at greater speed and at the same time put less stress on the motor, which will not heat up as much.

[strokkur]

Well a week later and second wetting. Took Malcolm's advice and fitted a smaller propp - 30mm 3 blade that I happened to have. Realised at that point that the original was actually a 40mm not 35. Wow big difference in performance - planes nicely at at about 75% throttle - 'does a wheelie' at full throttle and is err.....    well exciting shall we say - probably need a bit of weight up front perhaps? So thanks for that Malcolm  .

The motor still gets hot - not quite as hot I would say but still too hot to touch, no loss of performance for the 25 minutes I was sailing. I think I will have to think about watercooling but have resisted so far as it means some qute tricky keyhole surgery to remove the moulded mount and put in a new one with room for a cooling coil.

The only other hiccups which curtailed the testing was some water getting in through the rear hatch - think I'll add some sort of rubber seal and a catch. The bigger hiccup though was the forward superstructure which latched by sliding forward - a tongue engages in a slot at the at the front  and 2 wire hooks engage in 2 little boxes at the back. Unfortunately when buzzing round the lake it slides backwards. This was initially irritating as it's harder to lift out of the water with the top loose but potentially disastrous when I bumped into a buoy  , it almost slid off sideways and I had to very gingerly test slow speed handling as I steered into shore. Another catch to install I think.

All in all it seems to work very well. Well done Model Slipway for providing me with a relatively pain free introduction to model boating.

Cheers, Sam

Oh and the anchor fell off.

[Martin (Admin)]

Nice job Sam!   

(  Topic merged and renamed.  )

[strokkur]

Thanks Martin.

And I'll try and control my shotgun posting in future   

Cheers, Sam