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[grump52b]

 hi guys i used to run power boats a long time ago and i saw this part built percasa mtb i have to run on electric so this is my question it has a propshaft fitted and thats all which motor would you think might be ok i dont think i can run to brushless with all the extras so would likesome advice a reasonable turn of speed would be nice but im just starting over again and its all so different with the electric ones please any help would be great iv seen 600 and 700 motors very reasonable but dont know if they will be any good for the boat thanks andy (grump52b)

[gwa84]

first i think we would need the length width and depth or the boat and a pick of the prop shaft set up before eny advice can be given 

[grump52b]

sorry i forgot the boat details its 42" long about 9" wide and 6" deep im over in west yorks cant do power only in kieghly im told so ill have to go electric but it seems so complex with brushless etc hope this helps thanks again andy

[treeboa]

what you after scale speed, above scale or   mental speed, the 900`s are reported to give a good speed if you want to stay with brushed


also is she fiberglass or wooden hulled ??, whats her wieght, im building one at the moment that i started years ago, at that time i had fitted three shafts, initially i was going to power it with three re750`s, after watching one fail the other day im going with three cheap 600`s off ebay

[grump52b]

thanks treeboa its a wooden hull id like it to plane at about halfway down its length if possible i have thought of two motors but have been told one has to run backwards ?? to stop boat turning one way all time ?? now i dont know so if thats rubbish id  like to know but wuold still favour a single prop as its what im used to dont want mental speed but any pinters to engine size or type would be great just to get me going with it thanks again andy (grump52b)

[treeboa]

i have always run one motor opposite than the other on twin shafts, so cant really comment on any turning caused by both rotating in the same direction

the mates wooden hulled perky was considerably heavier than my glass one, he had two torpedo 800`s in his but it never really looked that good, 850`s would have no doubt improved it, personally if funds allowed i would go with a brushless setup and have a shuftie in search for pointers on which setup to work with your hull, if from this you decide to get a glass fiber hulled perkasa you then have the powerplant to transfer over

[grump52b]

thanks again treeboa i know this may sound stupid to a seasoned boater but how can you make one motor run the opposite way to the other one in the boat and what would i need to make it do it im away over banky seeing grandson over on the darkside (lancashire) so i wont be back on line till tuesday but thanks for all advice so far andy (grump52b)

[john s 2]

To make a brushed motor run in reverse.just swap the leads on the motor.Please remember that you will need handed propellers,John.

[treeboa]

your biggest issue on a wooden hulled perkasa is removing one shaft and replacing it with two, a lot of the original builds have the shafts bonded to the spine that runs central in the hulls and  a lot less room because of the ribs, top get decent access you may need to remove the deck  , if shes a nice build with a fair bit of decent detail you may not want to do this

i was chatting to someone the other day, they mentioned the thumper 5055 brushless motor as an electric replacement for an ic, i dont know as this brushless `electrickery` is all new to me

[Number 6]

your biggest issue on a wooden hulled perkasa is removing one shaft and replacing it with two, a lot of the original builds have the shafts bonded to the spine that runs central in the hulls and  a lot less room because of the ribs, top get decent access you may need to remove the deck  , if shes a nice build with a fair bit of decent detail you may not want to do this

i was chatting to someone the other day, they mentioned the thumper 5055 brushless motor as an electric replacement for an ic, i dont know as this brushless `electrickery` is all new to me

Call me daft but why not leave the centre shaft in place and cut it down with a dremel or similar? I would think that was much easier and less risky than trying to cut it out altogether? It could be cut down and twin shafts installed around it, not perfect but less risky and you'd not see it in the water.
I've got same dilemma with my HMS Exploit, built with one shaft, real one has two. Goes well and got fair run time with one. She's got wooden hull so no mean feat to remove the shaft. If I altered it I'd just cut it down and leave well alone, Dave. 

[tonyH]

Why not leave the centre one anyway and fit a couple of the motor/shaft combined units (Graupner/Robbe?) to the sides and run on 3? Centre one could then be for pootling about and the wing motors come in for planing. Possibly then 3 540's or similar.

Tony

[grump52b]

thanks a lot guys my percasa hasnt any detail on the deck other than the deckhouse in centre and thats been painted yellow and the hull blue so as you can see anything goes the centre shaft is in i now understand the second shaft just swop pos and neg on motor i am going to do it in battleship grey eventually and add some detail to deck after stpipping off blue and yellow paint the guy who built said when i sail it i cant see it too far away so i painted it bright colours ?? i know what an 'bottom' nice build but lousy colour scheme so its like i have a shell with one shaft and all the rest is up to me this electric stuff is a new ball game but i will get to grips with it thanks for all help so far everybody no doubt i will require more help thanks andy