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Author Topic: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?  (Read 3762 times)

bigbloke

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Hi All

'leccy boat rebuild getting nearer and nearer having discovered a cheap source of ESCs about 2 miles
from me (web shop!)

got to think now about fixing the motors to the hull.

The flat bottomed hull is too thin to fit countersunk screws although I could fit a brass plate outside to act as an additional heatsink and countersink into that . but that approach also adds drag.

I am mindfull that the 2 motors (JP power 400s)  are pretty high torque and have melted / ripped out the screws from their legacy fixings before. Hence I am planning to use "L" shaped metal mount brackets with a larger footprint.

I have a glue gun with both 120 and 200 degree sticks

I have araldite

I fear that using resin will melt  / deform the bottom of the boat

So time to turn to the collective experience for guidance !

what does the Panel think please ?

regards

BB

P.S. what "power" of servo please for a twin 400 powered mid-30 inch boat with a 50mm long rudder :) ?
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Martin (Admin)

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #1 on: January 24, 2013, 10:26:22 pm »


 Can you post a photo?  :-)
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bigbloke

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #2 on: January 24, 2013, 10:29:40 pm »

have to be tomorrow as the boat is in the attic and the kids are asleep

its a cheap and nasty ebay plastic hull . waiting on delivery of the cooling coils before buying / making the brackets. But my 7 year old will love it

Regards

BB


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wartsilaone

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #3 on: January 24, 2013, 11:18:44 pm »

I made a flat plate that matched the bottom of the motor mount. The bolts that hold the mount to the plate are heads down so you can replace the motor if you need to.
I used Polyester resin to secure the base plate to the bottom of the hull.

Ali
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wartsilaone

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #4 on: January 25, 2013, 09:49:39 am »

Photo.
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bigbloke

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #5 on: January 25, 2013, 11:17:52 am »

hmmm...trying to upload 5 x 36kb photos killed the forum mysql script ??

I'll upload one photo per reply and see if that works better ??

Regards

BB
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bigbloke

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #6 on: January 25, 2013, 11:19:10 am »

OK Pic 1 attached

Showing the overall boat when the hull is together
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bigbloke

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #7 on: January 25, 2013, 11:19:56 am »

Pic 2

This is the lower half of the hull overall view
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bigbloke

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #8 on: January 25, 2013, 11:21:24 am »

Pic 3

A close up of the legacy starboard engine mounts that will be ground off and replaced by a metal "L" bracket
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bigbloke

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #9 on: January 25, 2013, 11:44:04 am »

Pic 4

showing the appalling "stock" rudder mount

The rudder was literally "screwed down" into one position and was only used to "ratchet" the boat in a
single direction . vector steerting (one motor off one motor on) was originally used to steer it but this is being replaced with a sturdier rudder  that hopefully wont let water in !!

Foreward of the rudder is a screw post that holds the upper access panel into the hull. this prevents mounting a servo directly in front of the rudder assembly. Im clearly going to have to move the rudder
servo to one side but theres less than an inch of vertical  clearance and hence I'm unsure whether a full size servo will be needed or whether I can get away with a lesser powered slimline one ?

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bigbloke

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #10 on: January 25, 2013, 11:47:15 am »

finally pic 5

Showing the overall height of the rear of the hull which is about 1" external and 5/8 " internal vertical clearance making rudder servo mounting a bit challenging

The replacement rudder is significantly longer (55mm)

Regards

BB
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vnkiwi

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #11 on: January 25, 2013, 06:40:55 pm »

nice lookin' boat, be interested in following your thread and a video on the water when completed
cheers
vnkiwi
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bigbloke

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #12 on: January 25, 2013, 09:59:55 pm »

I'll start a new thread come the rebuild. still amassing parts presently.

three more deliveries then good to start :)

regards

BB
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pompebled

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #13 on: January 26, 2013, 05:25:46 pm »

Hi BB,

I have the same hull hanging on the wall in my workshop, waiting for a refit with a 1000 - 1200W brushless motor (single drive) which will get it planing (I hope...).

Unless you reduce the propsize, the two JP power 400 will struggle with that hull, most likely overheat and die, as it'll never get on the plane with so little power.

As long as it's on the market, this 'boat' has been the subject of many attempts by many boaters to make it run the way it should, but it's just too heavy for a NiMH/brushed set-up...
Only a high power, lightweight set-up  will make it plane, but only after the runnning surfaces have been adapted.

Getting this boat to fly takes skills and experience in setting up hydroplanes.

Regards, Jan.

 
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bigbloke

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Re: Plastic hull, metal motor mount ...screws / hot-melt / epoxy / resin?
« Reply #14 on: March 03, 2013, 09:29:22 pm »

Hi Jan

Thanks for your feedback

Whilst I see your point entirely, this boat will be used by my 7 year old son as his first boat.

I dont want it to "fly" per-se in inexperienced hands , just to go "fast enough" to keep him amused

Im sticking with the 400 motors as that's what I had on the shelf . When he's mastered control of it and wants something to go faster
we can either uprate the internals, wait to see what "Santa" brings  :-)) or he can save up his own pocket money!  ok2

The 400s will either have an illustrious but brief history! or they will be hammered for a few weeks and then back on my shelf
if he doesn't take to it

regards

BB




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