What glue to use to mount the motor mounts to hull

[Bushmen77]

Hi guys,
What glue do you use to glue your motor mounts to the hull with? It must be thick I just have no idea what to use. Thx for Your suggestion it .

[Shadow99]

90 percent of the time I use epoxy with a small amount of micro balloon filler, to thicken it up, so it doesn?t run to the bottom of the hull.
Shadow

[fweasel]

You can use JB Weld, but I prefer West Systems G-Flex. I thicken it with 406 Silica filler to suit the application, but still prefer to lay the hull on an angle and only glue two sides at a time so the epoxy pools exactly where I want along the joint.

[Fluid]

I use JB Weld. Mix it and wait 20-30 minutes before applying it, this allows it to thicken a bit but doesn’t effect the strength.




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[Bushmen77]

Is that JB weld marine ?
Hay fweasel
Thx guys . The stuff that was used on my boat was nice
It held in place but when I removed the mounts I just had to flex each side like 10x and it finally broke free.

[RaceMechaniX]

Many like the G-flex structural epoxy which can also be dyed.
JB Weld works great.
I use Loctite Hysol 120HP epoxy. This is a similar toughened epoxy like G-Flex. I buy this from McMaster and use small volume mixing tubes to apply in the hull. You can also consider 60HP and 40HP.

-Tyler

[fweasel]

I do not use the marine JB Weld, just the standard stuff in the black and red tubes. I prefer G-Flex over JB Weld because it has a little more give to it. JB Weld hold great, but after tearing down some hulls with it on the motor mounts, it tended to release as one long piece once an edge was broken free, be that in a crash or flexing the part beyond it's intended tolerance. I think its rigidity in this case works against it.

Regardless, the key to a strong bond is surface prep. Smooth, glossy surfaces don't offer anything for the epoxy to adhere to. A light sanding with a coarse grit sandpaper as well as holes in the motor mount to allow the epoxy to flow through both allow more surface area and a strong bond.

[Fluid]

Anecdote: at a SAW race several years ago I ran my sport hydro into the bank vegetation at over 90 mph (thanks Wilmer!). The hull split and was totaled. I removed all the hardware etc. except the aluminum servo mount. That was attached with standard JB Weld. Even using a hammer and chisel I could not remove the mount from the hull without taking the hull floor with it. Now I use that s*** on everything!





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[RaceMechaniX]

Jay didn't Tony rescue the "LA Woman" from the trash bin and rebuild it?

[Bushmen77]

Hi guys thanks for the info,

I bought the G flex and made a test sample to see it . It’s great stuff and the little give is nice .

Can a little micro balloons be added to make it thicker?

With a 75 min set time how do you deal with that?

I understand why you want to do one side at a time to help control the spreading .

A little dam built around it would be the trick but too much work.
Thx a lot

[properchopper]

Jay didn't Tony rescue the "LA Woman" from the trash bin and rebuild it?

Just buffed it out a bit......

LA Woman 2 DSC05246-1.JPG LA Woman DSC05248.JPG

[RaceMechaniX]

That's a bit rougher than I remember. Sorry we are getting off topic.

[properchopper]

OK so here's some inside info from the secret vault of rcboatbuild about securing motors. Given that the common two-sided motor mount has a markedly small contact patch with the hull, and although premium stickum [G-Flex, JB Weld etc.] will hang on really tenaciously, I've always upped the contact patch at least (according to a statistic that I just made up) 713.661 %.

Early on I made wells to contain larger quantities of epoxy (easily filled with epoxy syringe) - I'm a big fan of West System G-Flex

cheetahmount3.JPG cheetah mount DSC03974-1.JPG

Next version simply added some wood stringers to the motor mount side plates which greatly added to the contact patch between the stringers and the hull - on V-hulls I belt sanded the contact angle for max contact .

Cyberstorm rail mounts 20200901_100456.jpg

Used added length in front for ESC mount (anything look familiar Tyler ? )

sprintcat rails esc 20200901_100418.jpg

made nice way to secure hoses.

sprintcat rails tubing 20200901_100359.jpg

May sound like overkill but I ship worldwide and don't want anything to break, ever

BTW West Systems has Black tint for their G-Flex -https://www.westmarine.com/buy/west-system--502-black-epoxy-pigment--16900714?recordNum=2

[jaike5]

I believe that's my Q-cat. Tyler has beefed up a couple of my 40160's.
cheers, Jay.

[Bushmen77]

Hay copper good idea . I was thinking to do the same box like but wax it and pull off. I see your way to just leave it one is much better. Thank for the pics .

What do you use around the stopping tub? Is it a O ring tacked down with super glue?