Jeremy_H

With the control rod outer sticking through the 3/8 hole in the rudder plate just seal the boot to that, use some tubing to increase the diameter.

I'd like to see a pic of your boot though, the tapered ones I'm familiar with are intended to be fitted into a 10mm hole, 3/8 would just be a bit more of a squeeze, they have undercuts to locate within the hole. I'll get a pic...........................

Jeremy_H

Are yours like these?:

arcdude

Here is a pic of what I've got, this is not an exact pic the ones I have there is more ribs in them similar to what you posted but the base is similar and easily removed depending on what I come up with. Ordering one will likely take up to a week or so and I'd really like to get this done so I've been rummaging through all my parts box's trying different tubes in combination to glue onto the end of the outer tube.

arcdude

After digging through every nook and cranny of the house and garage I came up with a solution to the boot problem. What I ended up doing is making a new boot base that will fit through the rudder mount and be wide enough to slip the rubber boot on with a snug fit. So I located some Bi-Fold door parts pictured below which is the nylon insert that is tapped into the wood for the door to pivot. I modified the insert by cutting it down as shown and drilling out the center to fit the control rod outer shaft. All that is needed to be done is figure out what glue will adhere the nylon insert to the rod, trying Gorilla glue as an experiment and will test that in the morning after it sits overnight. The boot rests perfectly between the mounting bolts of the rudder base and has a little tension on it to keep it snug and water tight.

arcdude

Question for you Jeremy, when you used just the plastic control rods in your boat without a rubber boot did you use any kind of lube in the tube to prevent flow of water or were they dry? Thanks

arcdude

I now have a completed rubber boot and connecting rod that screws into the nylon inner tube in the hull. In the pic it looks long but the larger ring in the middle of the boot is the grommet which will be sucked down a little when I glue it to the outer tube at the transom. The Gorilla glue works great on nylon at least in this instance where one tube is snug over another and the surfaces are well scored to aid adhesion, I was unable to pull apart the test parts.

arcdude

After trying different methods of mounting the flex cable for the throttle I almost gave up in defeat and looking around my desk of odds and ends I noticed a heavy duty swivel ball connector and a light went on. What I did was take the ball out and use a piece of medium fuel tubing and placed it over the flex cable which fit quite snugly and inserted it into the ball opening in the connector and tightened the screw. There you have it a flex throttle cable stand off for the difficult spots with no clear option to mount the cable, This gives a stand off of 3/4" and when I installed the bolt into the bottom I noticed it is threaded all the way down so it can be shortened a little if needed. Once it was snugged up in the connector I found the more silicone tubing that was used it lessened the chance of it slipping, about an inch and the cable is quite secure. An added benefit of this is it allows some angle movement when attached and the cable length itself is easily adjusted. This is one I had to share, I'm certain this situation has stumped many. In the pic on the left the complete assembly is shown with the ball removed and on the right is a ball connector assembled.

fuma

i like the flex cable stand off. how are you attaching it to the hull ,radio box or motor mount? wonder if that would work on my outboards......................................... ....

arcdude

Think I really stumbled onto something here, it can be mounted just about anywhere a 6-32 bolt can be put through. It can also be used as a guide for a solid rod as well with a piece of nylon tube inserted for a lot of situations. What I've been faced with is a rather tight location in the mount frame for the engine with about an inch space in width and the same on a downward angle and the frame is 1/4" aircraft ply with aluminum angle in all corners. With this location being so tight and aluminum it was a real challenge to find a solution, so what I'll do is drill a hole down through the top plate of the mount and screw into the connector. I will post close up pics of the install later on so you can see exactly how I'm going about this. Cheers

arcdude

The stand off is a huge success considering it's size. Here is several pics to show what a difficult spot this was to come up with a solution for throttle cable support. What I did was shorten the connector 1/4" which leaves about 3/8" for the bolt to be threaded into and made a rubber washer out of an old inner tube that I keep for just these occasions. you can see the single point of attachment where the shiny #6 bolt head is on top. Here is the end result.

Jeremy_H

Neat solution arc, nice one. Liking your ply paint edge quality clear in those pics too!

arcdude

Thank you kind sir, sometimes it's the small things that count. I still have to give the whole boat another going over once all the fiddling is done with, it is coming along nicely I believe this was my last item I have to invent to get this put together, hopefully.

arcdude

May have another minor obstacle to figure out, the Hitec HS-81 servo arm is quite short in comparison to the arm on the ST 90 and even if I use the shorter throw arm hole the servo may not be strong enough to handle the throttle barrel. I would much prefer to use the outer arm hole in the throttle barrel for leverage to ease the load on the servo. Has anyone else encountered a similar set up, any suggestions?

Jeremy_H

At 2.6kg @ 1cm it should be fine on it's outer hole. You could work out it's limit at the operating length easy enough.

arcdude

I purchased a Futaba 3PRKA (not an expensive radio) and it seems a good portion of the travel in the throttle is dedicated to braking ability for car use at the expense of travel from idle to full. I may get away with a swivel ball connector on the lower hole in the arm and as you mentioned the servo should have enough strength to do the job. In rotating the throttle barrel it seems a little stiff so that was my concern, the engine if memory serves is only barely broken in and should improve. Cheers

arcdude

After days of being stuck on the throttle throw limit I'm no closer to a solution. Tried every conceivable variation in setup, end point, cable length and adjustment I can try and am still unable to get enough throw length being short by approx 3/16". What I've ended up with is when adjusted from the idle side upward the result is about 90 % throttle and if set up the other way around it'll be screaming with no set idle. The literature for the radio demonstrates throw length shortening and lengthening if coupled with an ecm and not available for a gas boat set up. There is plenty of length if I were to use a 46 size engine because of the smaller barrel diameter in the carb. So the only option left is to dismantle the radio and have a look at the throttle trigger and see if the transition point from gas to brake can be manually adjusted in some way. I have scoured the web and have been unable to find any internal diagram's to answer my question so has anybody taken a Futaba 3PRKA apart and possibly shed some light on the situation it would be greatly appreciated

Jeremy_H

I'm not familiar with the specific radio, but the self centralising mech is usually a tensile spring tensioned arm, this engages in a flat on the shaft that connects to the potentiometer. Having removed the spring, possibly the arm too, you'll need to rig a new spring to provide a return to idle function, frankly through an elastic band around the brake spur on the trigger will do it. Having done that throttle trim can be used to act as engine shut down.

arcdude

Opened up the radio and am unable to access the mechanism for the trigger because the circuit board is soldered to it after assembly and partially covering the mounting screws for the unit and not being familiar with the specific components, heat and so on I'm best advised to leave well enough alone Your suggestion Jeremy to use an elastic band, as simplistic as it sounds actually does help in throw distance and just may be the way to go in the interim until a more permanent solution can be found. One idea I had is to extend the throw arm on the servo by bolting another arm onto it to lengthen it or setting up a bell crank above the servo but that'll wait until winter to figure out, gotta get this creation on the water

Jeremy_H

Are you on the inner hole on the throttle arm?

arcdude

It is set up with the control rod in the outer hole on the servo arm and on the inner hole on the throttle arm and short about 3/16" give or take. For safety sake I'll set it up with the idle end enabled until a permanent solution can be found.

arcdude

Got started on the final assembly with the carbon rod tubes being the last thing to make. The COB is about 2.5" behind the trailing edge of the front sponson's so a good starting point.

Jeremy_H

Love it, looks viable. Looking forward to this

arcdude

Just about got the back end bolted up, the closeness of the bolts are too tight for the nylon lock nuts in the top brackets so I'll have to change them out for flat nuts and some loctite.

Jeremy_H

Quality work

arcdude

Thanks Jeremy, appreciate the compliment Managed to get the motor mount installed today, that is one tough mount, the boat will disintegrate around it before it came apart. Now onto installing the remote glow starter and engine