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[g7tmu]

Hi All

I have just aquired a Robbe PT-15 kit, as my first scale type build for a very long time!

I am hoping for some advice from someone who has built this kit to a couple of queries, to get me started.

Query 1 - The kit shows the use of a Robbe gearbox/motor setup, but I have heard that these are very noisy, which is not suitable for my model sailing lake, which doubles as a nature reserve, so therefore I am thinking of fitting a straight shaft/direct drive. I would be interested to hear from anyone who has done this as to motor type/battery voltage/ shaft length used etc.

Query 2 - The Robbe instructions suggest wiping the hull with thinners to prepare it for painting, which sounds a bit risky to me? Any ideas on a safer way to prepare the hull please?

Thanks in advance for any help you can give me.

Great site this, thanks Martin.

Victor (G7TMU)

[Daryl]

The thinners sounds a good idea as it gets rid of grease/ release agent etc and makes a clean surface for the paint to adeare to. So far I've not had any miss-haps using thinners, I have two Robbe motors with gearboxes on a US crusier I am building with my son. the motors came with the hull, we took them apart and applied lots of grease inside as I thought when I spun them around they sounded noisey. I have yet to attach them to a battery but I wouln't be supprised that they sounded awful. If they do, one option I have is to put them in a sound insulated box cooled with a fan. this should deaden the racket a bit and the hull is big enough.

But best laid plans etc etc.....

Regards
Daryl

[chugbug]

 :(? I can confirm that the Robbe motors and gearboxes are very noisy indeed but due to the build of the PT boat once finished would be very difficult to replace
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Chugbug

[Martin (Admin)]

Hi Victor,
Robbe and most basic gearboxes (non metal geared, ballraced etc)  can be quite noisy but nothing like an IC (glow, nitro) engine, they are just noisy compared with a straight drive from a motor. The 'noise' people are speaking of is like the gearbox noise from a car going in reverse, it's just noisier in comparison than going forward! :-\

I also have the Robbe PT-15 kit ( unstarted.... another whim!) and have built a couple of Robbe kits with ABS / Plura hulls. ABS etc. is quite an "oily" type plastic and this can effect the gluing process. Best this to is, lightly sand (key) the area where you will be gluing, wipte down with meths (or safety solvent, turps etc or wash down with soap and water - as always, test on an offcut is unsure!

I use superglue for most joints these days, 'Stabilit' or Devcon 'Plastic Weld' where I want a high strength joint ( shaft exit, rudder post etc.)

Any help?
Propshaft.

[Colin H]

Victor,

I have just finnished spraying a Robbe Atlantis (Plura) hull. Had no problems with wiping down with white spirit. Then when dry first sprayed an adhesion promotor BEFORE primer.

Hope this helps Colin H.

[ukengineman]

Victor,
I have made a Robbe PT15 and operated it for a couple of years. I have sailed it at Beale Park several times and answered people's queries there.
I can confirm from other PT15's I have seen that the Robbe gearbox is very noisy. My boat is powered by an MFA Torpedo 800 (please note NOT the 850), this drives a 50X prop. The battery pack is either a 10 cell 2400 NiCad pack or a 10 cell 3300 NiMh pack. This combination may sound a little unusual but it gives good planing speed, very quiet operation and excellent duration.
Regarding the use of thinners, I would say no - I would recommend the use of isopropyl alchohol (you can get it from Maplins).
One final point, and this may be the most important. When bonding to the ABS parts (eg hull and deck including wooden deck cross members) you must use Stabilit Express as per the instructions. DO NOT use epoxy - it will not give a proper bond. I have done tests to destruction to confirm this.
I hope this helps, Alan

[Adzam]

hi there
I built a PT15  about 4 years ago, seeing regular use, unfortunately i used teh rcomended robbe gearbox and motor assembly. if was to do the build again i would do a direct drive or even a olympus belt drive setup. possibly even two 380 direct drives ??
the robbe gearbox assenlby is about teh same level as a electric garden strimmer !!

 as for the cleaning of teh hull i would go for the alcohol answer , as for bonding, i never used stabilit express as recomended by the instructions, but a long set  2 part epoxy resin, and i have to say no complaints , but everyones experiences are different   :)

[g7tmu]

Thanks very much for all the help, just shows how useful this site is!

I have started on the PT-15 build, with the stand made and the hull and all hull fittings trimmed already. I am going for a direct drive install and have made a motor mount, so that I can work out how best to install it.

Thanks again

Victor (G7TMU)

[Colin H]

Hi Chaps,

Should have read the original post more closely. In my Robbe instructions for Atlantis there is no mention of thinners but White Spirit as per my original post.

Went out this afternoon and wiped some thinners on to scrap plura for test B---dy awful mess.

Yours Colin H.