Tether junction and cable junction sealing:

Post date: Aug 01, 2015 2:44:7 AM

Components:

Garden cable junction pipe IP68

Wine bottle sealing Wax:

Cellpack 2 component powergel:

2 components epoxy material:

Marine grade silicone sealant:

The making:

3 holes have been made to pass the cable junction through the hull and the 3 cable junctions from Garden cable junction pipe IP68 passing through the hull have been fixed first with silicon glue than by a thick layer of epoxy 2 component material.

The 2 long bolts used for the motor frame fixation are fixed on the outside of the hull by adding a much thicker layer of epoxy material.

The surface of the PVC pipe in contact with the epoxy has been sanded to increase adherence.

Prototype ready to be silicon sealed and waxed Epoxy to hold the bolts for the motor frame holder bolts and nuts.

Sealing the cable:

For our first try to seal the cables we used only Wine bottle sealing Wax to fill up the junction pipe (beforehand the inside have been paper sanded to increase adherence) but the wax, when melted, is too liquid to properly fill the hole.

This try didn't pass the first water tight test and water was pissing in the hull from the motor cable junction.

We did another try by filling the bottom part of the cable junction with Marine grade silicone sealant then let it dry for half day and fill it up with Wine bottle sealing Wax.

I found out 20 more meter of cat 5 ethernet cable, so i did an extension cable junction by soldering the 4 pairs and insulate them with heat shrink tubing and seal everything inside a plastic film canister fill up with Cellpack 2 component powergel.

We have attached a stainless steel ring on the motor frame to fix a 30m dacron line (from my 300m kite line) all along the tether to put the pulling tension on the line and not on the tether itself.

Lighting from diving lamp:

From a sanded surface on the PVC pipe and 2 components epoxy material we have glued some stainless-steel hose clamps to hold to (8$ Chinese made diving torches)

Now it's time to make a watertight dive....

Watertight Dive:

Hugh is ready to bring the ROV for watertight test.

After one month of interruption in the project development due to the resort being busy busy in august, we finally could resume the work and made a watertight dive test .

Hugh have bring the ROV at 12m depth with the full tether length submerge (except for the connector of course) and we leave it here for one hour.

The test was a success, not a drop of water went in.

The tether plus the dacron line is negatively buoyant and get stuck on the bottom, we should find a solution to add small float on the tether to make it neutral or slightly positive.

To setup the gravity center of the craft (CG) and obtain a slightly negative buoyancy we have used 3 lead bars of 1 kg each (as fixed ballast) that are fixed inside the hull and are attached with Velcro's so that we can slide the bars inside the hull to adjust the CG. To fine tune the CG we attached under the hull with rubber rope a 500gram lead bar that we can slide along the hull.