big problem with proboat coast guard boat - RC Groups
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Nov 26, 2011, 11:11 PM
Registered User

big problem with proboat coast guard boat

I tried to install universal connector(in the green box), as the original connector is so binding.

when I play with the position of the motor rack, things happen.
One of the nut that stick behind the wooden box has fallen off - the red circled place. I cannot feel the thread at all, while the other three have proper nuts.

Do I have to take off the whole thing to put the nut back to place?

I saw the wooden structure are inter-locked and glued very tightly. It is gonna be a big job then. Or I have to open a whole to the bottom of fiber glass hull, which destroy my boat's structure.
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Nov 26, 2011, 11:15 PM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
If you want to put a blind("T") nut underneath, and wood is tight to the hull, your options are limited.
Have you thought about using a threaded insert instead?

Nov 26, 2011, 11:41 PM
Registered User
MODELERCHINA- First off looking at the pictures you posted it looks like the shafts were really binding since the end of the stuffing boxes look like they discolored from heating up. The easiest way to correct the aliment from the motor to the prop shaft is by using a double joint universal.
Nov 27, 2011, 12:52 AM
1/2 a bubble off
Apismelifera's Avatar
Looks like there was a tee nut there already, or similar, factory installed, and it fell out when the motor was removed. I think that is what is indicated by the red circle.

The problem is how to reinstall the nut without cutting the bottom of the boat to get to it.
Nov 27, 2011, 01:24 AM
Registered User
CaptCB's Avatar

Blind nut repair

Install a threaded insert from the top. Oversize the hole to fit the insert. The flange nuts used for aircraft wood motor mounts, would work. Get the 2-56, or the 4-40 ones, and remove the 3 spikes. They are made by DU-BRO products. Any hobby store that has aircraft should have them. Install with a med CA glue. Be careful not to get glue in the threads. If you do, just run a tap through and it will be fine. I also, would get rid of the factory universals!!! The Dumas dogbone system, works great. CaptCB
Nov 27, 2011, 09:39 AM
Registered User
Thank for you guys input. My question is I cannot get to the bottom side of the wood piece to re-install the flange nut. in terms of threaded insert, can i screw it in from top-to-down? the wooden piece is about 2mm thick, does it enough to hold strong with some CA?

I thought about dremel a round hole besides it to allow finger in, but again it is tight and screeze.
if i open a hole from bottom, it is even more nasty, and what if the other 3 are fallen off?
or I gonna move the motor off from the original place, which require to re-build a new base and glue or screw new base to the existing one.
Last edited by modelerchina; Nov 27, 2011 at 09:52 AM.
Nov 27, 2011, 09:47 AM
Registered User
Originally Posted by frankg
MODELERCHINA- First off looking at the pictures you posted it looks like the shafts were really binding since the end of the stuffing boxes look like they discolored from heating up. The easiest way to correct the aliment from the motor to the prop shaft is by using a double joint universal.
it may be hot, but the black you see on are mostly lubes that mess up from the prop shaft. i bought one step joint universal, in the green box. and then trouble happens.
Nov 27, 2011, 09:59 AM
Registered User
A trick to reinstall the blind nut is run a piece of wire down through the hole and keep feeding it till the end reaches a open area where you can get to it. Then insert the blind nut on the wire and tie a knot at the end of the wire. Now pull the wire back through the hold till the nut is pulled back into the correct location. Now comes the tough part. Take a long screw that fits the blind nut and put a very light coat of grease on the threads. Now cut the wire and it should fall out of the threads and carefully thread the bolt in without pushing the nut out. Once the bolt is threaded in now apply CA while pulling the nut in the correct position. The grease will keep the CA from gluing the bolt to the blind nut and out of the threads. Good Luck.
Nov 27, 2011, 01:11 PM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
Threaded inserts match the thread of your bolt on the inside, and
are slotted on the top and threaded on the outside so they can be
inserted from the top of a mounting location.

Nov 27, 2011, 04:01 PM
Registered User
I see the point, ordered some this, my screw is M3, probably the #4 as per wiki about screw size. thank you all guys.
Nov 27, 2011, 04:06 PM
Ed Croughwell
modelerman's Avatar


Maybe these might help. If this link doesen't work, the try a google search for "rivnut"
Nov 28, 2011, 12:58 PM
Grumpa Tom
Kmot's Avatar
Hi there modelerman. As an extensive user of those inserts, I would like to pass on a little experience.

If you have a set of calipers, measure the diameter of the barrel inside the threaded area. This is the part of the barrel that will be in contact with the edges of the hole. You do not want the hole to be as large as the barrel diameter. If it is, the insert will fit loose. You want the hole you drill to be slightly under sized to the diameter of the barrel. The packaging indicates what size drill bit to use but I have often found that recommended drill bit to be too large. I usually end up using a Number Drill as opposed to a Fractional Drill.

Once you have the hole drilled to the optimum size, start your insert to begin the cutting of the thread. Use a small square to be sure it is perpendicular to the wood plate. Then back it out slightly and apply a dab of epoxy glue. Screw the insert in the rest of the way until the top is just barely above the surface. Wipe away an epoxy with rubbing alcohol.

Another tip: Be sure to hold your screwdriver perfectly straight up and down when screwing in the insert. Any sideways pressure at all will snap off the brass tabs.

Hope this helps!
Nov 29, 2011, 02:59 AM
Registered User
CaptCB's Avatar

Threaded Inserts

My way of installation is different, drill the hole slightly oversize, and then run a tap in. I the screw in the insert, and lock it in place with Thin, then MED., CA. I have never had any inserts fail yet, and I tighten my motor mounts, pretty good. CaptCB
Nov 29, 2011, 09:42 PM
Registered User
excuse me for my english, what is " then run a tap in"
Nov 29, 2011, 10:36 PM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar


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