I can't for the life of me get the cooling jacket on the motor. Any tips? The o-rings just seem too big, but checked it's the correct cooler etc.

Lithium grease or dish soap usually works. The o-ring has to be a tight fit or it won't seal and, if that happens, you will lose all of your electronics due to water shorting out the components. Something else you might try is to throw the motor in the freezer for a few hours . The reason for that is the motor's metal parts will slightly shrink, giving you a bit more room. You don't want to do that with the jacket as rubber(and rubber like compounds) expand both when they get hot and when they get cold(back to beginning science on that one). If you try the freezer, DON'T TRY TO SPIN THE MOTOR UNTIL IT WARMS UP OR IT CAN DAMAGE IT. As you are probably aware, different kinds of metals have different expansion rates so getting it too cold could damage some of the parts if they contract either more or less than others around them

I ended up breaking an o-ring, doh! Got the other one on but took a little chunk out of that too. On enough to mock it up etc but will have to get new rings and try again.

This is the mounting spot for the rudder on the plans, do you think it's ok or should be closer to the center?​​​​​​​

https://cimg1.ibsrv.net/gimg/www.rcu...f50411ba5d.jpg

I would move it in so that the pivot pin is centered on the stringer. Otherwise, looks good

This is what I'm thinking for the bend in the stuffing tube. Is this gentle enough?
https://cimg5.ibsrv.net/gimg/www.rcu...109b1756e5.jpg

It looks like this will have to be the layout. To get the batteries in the ESC will have to go toward the back with the servo. It will mean running wiring fair way but not sure how to avoid that/

https://cimg8.ibsrv.net/gimg/www.rcu...00cb4ac90a.jpg

The motor is currently 1/8" from the bottom of the tunnel. I could get it lower but it would mean a hole in the tunnel which I'm not keen on.

https://cimg7.ibsrv.net/gimg/www.rcu...fc3adc1c1c.jpg

So, you're saying the ESC won't fit forward of the motor? IF it will, it would work better to reverse the batteries, leads pointing forward, and connect the batteries with a "Y" so you will have the batteries in either parallel(longer run times, less speed) or series(more speed, less run time) as you desire. The shorter the wires, the less voltage loss and less chance of burning up a wire. Having the receiver in the back would be better, weight wise, since the receiver is several grams lighter, on average, than an ESC. You could move the motor aft a bit, giving more room for the ESC in the front as well. Is the ESC water cooled? That could make a difference in location as well

I could get it right up in the nose but I'd have to route out some timber to get it lower in the chassis.

It would mean it's right next to the motor. Cooling would be tricky but could go either side of the motor and then back over the top.

https://cimg9.ibsrv.net/gimg/www.rcu...c6ae28beb1.jpg
https://cimg0.ibsrv.net/gimg/www.rcu...26f621c6f9.jpg

I could also mount it above the stuffing tube, it would need a mount I can easily remove. The nose option might be too tight, might get hot jammed in there?

https://cimg6.ibsrv.net/gimg/www.rcu...bbca7f7df1.jpg

I think it will have to go in front of the motor and the motor will have to move back. Either way I'll have to figure out the cooling lines. The timber either to the side or in the nose will have to be modified to get the cooling in there. I weighed it and the balance is pretty much 50/50 as you see it here so it may not be a huge issue.

https://cimg9.ibsrv.net/gimg/www.rcu...0810d2463c.jpg

And that, my friend, is where R/C boating gets fun. Figuring out how/where to run wiring and lines is where it gets challenging. I've got it pretty much down as for the nitro and petrol boats but, with the electrics, still trying to figure that one out since there are more parts involved

Well, had a very interesting experience with carbon cloth. I tried to put it down the tunnel one night when the kids went to bed.

What I learnt:

1. Carbon cloth frays like nobody's business, and the runaway threads like to stick to anything with epoxy on it.
2. You need to be better prepared that I was.
3. It's hard to get it smooth and neat.
4. It takes about an hour to clean up the mess you've made just to get back to square one.

Once I'd done that, I just ran some epoxy into the tunnel, thinking that'll be strong enough. Going to do the same in the seams of the sponson's and that'll be that.

I have glued in some fibreglass panel to mount the motor mount to, and made a motor mount out of the same material. Because there is a tunnel, I've mounted the motor through this mount so it sits down in the tunnel, about 2mm above the floor, and gives me a good angle.

Glued it all in tonight so fingers crossed.

ESC now goes into the nose a little as that portion of the nose is covered by the cowling so the motor wires can come back through above the deck. Next I'll get the stuffing tube mounted then I can move on to making some brass lines for the water to leave the boat. Slowly getting towards decking it which is exciting but plenty to do yet. We're in lockdown here in Sydney again so getting a bit more time to work on it though obviously which it wasn't due to the bug.

https://cimg4.ibsrv.net/gimg/www.rcu...bf5dfc7502.jpg

I've also printed up a servo mount on my newly acquired 3D printer. It's the same weight as a standard servo mount (which didn't fit) but custom made to fit the boat. Noting that I'm not using that linkage, have something better on the way.

https://cimg5.ibsrv.net/gimg/www.rcu...b5faca568e.jpg
The CAD design.
https://cimg6.ibsrv.net/gimg/www.rcu...ea6f30ca81.jpg
I'll get a better photo later but this gives you an idea. Most of it will be under the deck so this way I can mount it to the bulkheads rather than the floor. Easily removed and less floor holes.

Just realised the stuffing tube doesn't fit into the end of the strut. Pretty sure it should? It's too big.

Have emailed the supplier.

These little delays really slow things up. I've put a heap of auto filler on the plug for the hatch, and it didn't go off. So I'll have to fix that. Having real trouble getting the ratio of that right, as it's supposed to be 50 to 1 product to hardener, and that's hard to judge in small amounts.

Plugging along slowly here, I think I'm 1 x stuffing tube mounted and one creation of steering fin mount away from sealing and foaming.

Is it normal to only get a small amount of left hand steering? It seems to me the mount pulls the rod over into itself. Might not be an issue considering I'm intending to turn right?

https://cimg6.ibsrv.net/gimg/www.rcu...0ffa901b27.jpg

No, that's not normal. The issue is that the pushrod is hitting the side of the hole and not allowing room for the rod to move sideways, thus giving less ability to turn the rudder to the left. You could fix this in one of two ways:

1. make the threaded part of the pushrod long enough so that the tube won't be in the hole
2. see if there's room to widen the hole so that the rudder's pushrod has more room to move sideways.

I had a similar issue on my scale boat's throttle pushrod. I had to rework the pushrod seal where the rod enters the radio box to give it room enough to give me a full throw.
https://cimg1.ibsrv.net/gimg/www.rcu...b2c6287869.jpg
https://cimg2.ibsrv.net/gimg/www.rcu...95b5edab54.jpg
https://cimg4.ibsrv.net/gimg/www.rcu...86d5b2a0a1.jpg
https://cimg4.ibsrv.net/gimg/www.rcu...f60ec1e891.jpg
The four pictures I posted are of the transom and rudder assembly on my scale boat:
The first shows how large of hole the builder drilled to feed the pushrod through.
The second shows full left throw.
The third shows full right throw
The last shows the rudder centered.
One thing I should make sure you're aware of is that the radio is programmed to have more right throw than left. In fact, I have the left turned down to 50% throw to keep me from rolling the boat in a left hand turn. I also slowed the servo down to 50% speed as well. I found the rudder reacted way too fast at full speed, for me anyway, to make the boat easy to drive.

Thanks HJ,

It's actually not hitting on the hole, but the side of the rudder mount itself. Looks like I'll have to try to get the threaded section longer.

Thanks again.

I was guessing, for the most part, due to the angle your picture was shot at. Would it be possible to put a radius into the side of the bracket to clear the pushrod? As you could probably tell, the bracket on mine was made overly wide to make room for the pushrod, not exactly the set up I would have done but, you know how it goes, you deal with what you have and make it work

Brilliant, I’m sure I can do that. They seem like such big openings in all the boats, how do you keep water out?

On my scale boat, I don't worry about it. The radio box is all the way at the front and, when the boat it running, water doesn't get in. I just dump it out when I bring it in and I'm ready for the next heat. You will have to use a seal of some sort. Check out the bottom of this page:
Boots & Linkage | Rc Boats by OffshoreElectrics
I used one on my throttle linkage when I found the seals that were in the boat when I bought it wouldn't work with my reworked linkage

Currently building a turn fin, so nothing much to report. Advancing slowly though.

I've been doing lots and updating little!

Motor mount is done, stuffing tube is in, cooling exit lines ,are in servo mount is 90% done, turn fin is made and installed and transom all glued up (just now).

I have some small bits and pieces to do and I can seal it all up and put some foam in, and then install the decks. Crazy!

https://cimg9.ibsrv.net/gimg/www.rcu...fe9fcb897d.jpg

I'm going to 3D print the cowl now rather than fibreglass, so I'm in the process of learning how to 3D model a complex shape like the cowl.

Nice boat

Cheers :)

Decks are going on, starting to look like a real boat.

https://cimg7.ibsrv.net/gimg/www.rcu...3fc28d96c6.jpg
https://cimg9.ibsrv.net/gimg/www.rcu...879a23a38c.jpg

I stand corrected!!!

How many boats have you built? And how often do you get to race?