Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: First project MTB  (Read 2495 times)

norfolknewbie

  • Guest
First project MTB
« on: September 16, 2006, 11:02:17 PM »

I have bought on e-bay a 39" GRP flat bottom MTB type hull and was wondering about the best combination of motor, shaft and prop to use. ( plus a good source to buy them from )

Is there a good beginners book to read for this sort of project as I dont have a clue about the angles of the prop where it penetrates the hull, distance and size of rudder etc.

Many thanks from a complete novice, Jim!
Logged

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,532
  • Location: Blackpool, Lancs, UK
Re: First project MTB
« Reply #1 on: September 17, 2006, 12:19:35 AM »

Have a look here.
http://pt-boat.com/
Logged
"With the right tool, you can break anything" - Garfield

Tug

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 163
  • Location: France [86]
Re: First project MTB
« Reply #2 on: September 17, 2006, 01:17:01 PM »

Jim! Don't look there you will only be decimated?

If its a first boat and you want to have fun then go for a single motor and prop angled with reference to the prop size and the motor height, but remembering that at rest you want the inside of the propeller shaft above water so it can't seep into the hull.

My patrol boat has three different motors/shafts and props, in a 3 foot boat there ain't much room but it goes well,
  in spite of the fibreglass hull being a crap moulding, can I say that? Certainly did not qualify the time and effort but it worked,
Logged
Junk is something you've kept for years and throw away three
 weeks before you need it.

norfolknewbie

  • Guest
Re: First project MTB
« Reply #3 on: September 17, 2006, 01:44:11 PM »

Yes....it was certainly a lot of reading to start with, but fascinating.

Can we start with a motor size and I will work from there? I am not looking for any great speed as the local boating lake at Sheringham isnt that big!. Cheers, Jim
Logged

ambernblu

  • Guest
Re: First project MTB
« Reply #4 on: September 17, 2006, 02:06:20 PM »

Jim,

There's a useful source of beginner info on Martin's main Mayhem site - http://www.modelboatmayhem.co.uk

Have a look under Technical bits at 'Starting in Model Boats', Electrics, Motors etc. As Tug suggested, a single motor will cause less hassle and at least allow a less sharp learning curve to tackle as you will need to understand and install all the other 'bits and pieces' as well! Keeping it simple first time around will be a bonus..  ;D

Not much help, but I haven't bought anything more powerful than a 5 Pole 545 motor, which i have in two of my fast boats, but they are both less than 30" in length and consequently will be a lot lighter than the boat you are planning, so would suggest you buy bigger for a single shaft drive.

Cheers, Brian
Logged

Shipmate60

  • Global Moderator
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,247
  • You bark - I will bite!!!
  • Location: Fareham
Re: First project MTB
« Reply #5 on: September 17, 2006, 08:37:09 PM »

I would suggest an MFA 850.
It should push it along ok, but doubt if it will plane properly on only one.
MFA sell a matched 2 blade prop too.
It is a 12 volt motor so to keep weight down you could use nigh capacity Metal Hydride batteries, but for duration a 12 volt 7 ah gell cell, but these are quite heavy.
These are quite common, so you could always borrow one and try it.

Bob
Logged
Officially a GOG.

Tug

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 163
  • Location: France [86]
Re: First project MTB
« Reply #6 on: September 19, 2006, 12:30:08 AM »

Thinks, [hard that]

I think it was Deans who did a motor called the Kestrel,

This runs a 3 foot-ish  Perkasa respectably on a a 7.2 NmHyd thing 3 Amp gives almost an hour sailing, bit of this bit of that

 Tug [I will look that 'nicad thing up one day]

[tonight I'm in Lancashire] ;D
Logged
Junk is something you've kept for years and throw away three
 weeks before you need it.

norfolknewbie

  • Guest
Re: First project MTB
« Reply #7 on: September 19, 2006, 09:54:59 AM »

Thanks Guys,

Deans looks like the answer for the whole package.  Stand by for more questions!

Cheers, Jim
Logged

cbr900

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,871
  • Mayhem is the Only Forum!
  • Location: Taree New South Wales Australia
    • Roys Hompage
Re: First project MTB
« Reply #8 on: September 19, 2006, 03:11:55 PM »

My PT Boat only has one motor it is a johnson 545  with 7.2 pack and goes if anything to fast with less than two inches in the water,
so one motor will work, run time is only about 40 minutes...


Roy
Logged
I try not to be naughty but nautical

Tug

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 163
  • Location: France [86]
Re: First project MTB
« Reply #9 on: September 19, 2006, 07:29:44 PM »

Roy,

Only runs for 40 mins...

Aha, but I said " almost an hour sailing, bit of this bit of that" I don't run flat out ALL the time  :-[  Tug

sykick me... forward thinking edit?

 At which point Roy, this shows that there is not that much difference between motors of simular size.
Logged
Junk is something you've kept for years and throw away three
 weeks before you need it.

cbr900

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,871
  • Mayhem is the Only Forum!
  • Location: Taree New South Wales Australia
    • Roys Hompage
Re: First project MTB
« Reply #10 on: September 20, 2006, 05:49:48 AM »

TUG

Neither do I mate, but just cruising around without going flatout, lucky to get it to last close to an hour, add throttle at all and 40 minutes...


Roy
Logged
I try not to be naughty but nautical
Pages: [1]   Go Up