Newcomer with a question

[Beaux]

Cool looking boat. There is a lot of good info on here so don't mind asking.

[Old School]

While I am awaiting the slow boat from China with my carbon fibre cloth, I have regularly revisited this project making little changes to the interior each time. My first thoughts were to simply modify the hull but still retain the original look of the interior with its plastic mount brackets. Common sense eventually dictated that the entire interior had to be scrapped and start with a clean sheet, regarding placement of motor mounts, servo, batteries and ESC. With everything cleared out I can now look at this project in a positive way.

My first question is in regards to motor placement. I have secured a 36 series longitudinal carbon fibre motor mount and need to determine its placement as it will be bonded to the shell after the shell interior has been strengthened with carbon fibre cloth. As the motor is relatively heavy should I position the motor longitudinal centreline over the C of G and then allow the batteries (one either side of the motor) to balance out the moment weight of the rest of the hardware (stinger and rudder aft and ESC forward of the motor on the centreline)?

I am taking the theoretical C of G as approximately 30% of the 'wetted' waterline measured from the stern.

[rol243]

its wise to place all gear in the hull and balance c.o.g. from there before the motor / mount is fitted , its not good to place batteries port and starboard in a mono hull as the V of the hull will amplify a bad balance . keep the batteries in front of motor when setting c.o.g. balance.

[Old School]

Many thanks

[Old School]

Upon receipt of my HK Osprey, I have removed the 3/16" stinger and now modified it to fit the 60 degree sloped transom on this hull. The sloping transom problem has now been overcome as both the rudder mount and the stinger are now modified to fit. Now awaiting carbon fibre cloth to arrive.

The Osprey had a two-piece flexshaft so this will not be used on this hull. Hopefully, I will be able to salvage the stuffing tube, teflon liner, dog drive and 40 mm propellor from the Osprey to use on this hull.

Edit: I have removed the stock stuffing tube from the HK Osprey and will fit to this smaller mono. I noted that the stuffing tube is two tubing sizes too small for the stinger strut tube, so have cut tubing to allow the stuffing tube a neat fit inside the strut tube. I will allow approximately 1/4" insertion and seal on final install. I will also fit a Speedmaster rotating bushing to the stinger with a one-piece flexshaft.

[Old School]

The slow boat from China arrived this afternoon with my carbon fibre cloth. I quickly set to work and mixed a small quantity of West System G-flex (designed for adhering to ABS plastic after first keying the surface with coarse sandpaper) with some chopped carbon fibre strands and filled the void in the hull as a result of me removing the old skeg.

Once cured I need to then complete the task of reinforcing the hull. I need to purchase some acetone, white vinegar and disposable brushes. I have never worked in carbon fibre but about fifty years ago I did do a little fibreglassing as part of my apprenticeship. Fingers crossed!!!!!!!!

[Old School]

This is my "kit" of carbon fibre cloth. When I lay the cloth the thin tape side will be unseen.

Edit: carbon fibre now added. I used a West System epoxy formulated for use with ABS plastic (G-flex). The use of white vinegar as a cleaning solvent has been a godsend, saving me a fortune in acetone. For a week or so I have been cutting the bottoms from empty plastic milk bottles to use as mixing containers for the resin. These were perfect. I am happy with the result, but it could have been better executed if I had a little more experience. I applaud those who carry out perfect results on their hulls.

[Old School]

I have hit a stumbling block installing my stinger. The transom is angled at 60 degrees and coupled with a 'vee' hull and the addition of carbon fibre to the interior, I have found that when the holes were drilled for the lower mount holes on the stinger there is no room to fit a nut and washer. The mount bolts enter the hull right where the transom intersects with the floor.

I have refilled the lower holes in the transom with an epoxy resin and feel that my only alternative is to use self tapping screws on the two lower mounts holes. This is not ideal but what alternative do I have?

[NativePaul]

Drill and tap a backing plate?

[Old School]

Drill and tap a backing plate?

Paul,
I wish that I could however, the threaded end of the mount bolt enters the inner face of the transom right where the lower edge of the sloped transom intersects with the floor of the hull.

[rol243]

can you fit Thread Inserts into the existing bottom holes then all you have to do is screw on the bolts.

[Old School]

Unfortunately not. I tried last night to enlargen the recess on the inner side of the transom to get a nut in there but to no avail. I have extended the stuffing tube through the transom about 1/4" - 3/8" so this will support the lower edge of the stinger tube, while still allowing some trim angle if needed. I feel the self tapping screws should be sufficient as in reality I have little choice.

Similarly with the trim tabs. These will need to be attached with self tapping screws for the same reason as there is no way a nut can be fitted to a machine screw mount. Also, I will have to revert to my initial idea of using the simple Traxxas Spartan stock release turnfins as mounting the 'expensive' fins I later purchased will have the same problem. There is just no room at the transom/hull interface to fit retaining nuts - the 60 degree sloped transom has caused me multiple issues.

[CraigP]

Can you get pics with a flashlight in there to light it up? Maybe someone can see an out of the box solution...

[Peter A]

How about this. Either use some epoxy metal repair, or build up the area with epoxy glue and when cured, drill and tap the holes you need.

[rol243]

you do know what a Threaded Insert is don,t you ? these will fix your issue.