Engel Type VIIc success and failure.

[Schmitty1944]

I ran my recently completed Engel VIIc for the first time (other than in the test pool) yesterday and had some interesting pros and cons.

Number 1) it has developed a leak somewhere in the stern bulkhead area that wasn't there when I checked a couple days before and will require me to take it pretty far back apart to find. One real downside of this model is when the two 750ml piston tanks fill with water it puts a significant amount of air pressure in the hull. All the seals need to be absolutely tip-top.

Number 2) My first time putting it in the water the rear piston tank would not move (fill with water). Every time I opened it up to check it worked fine, eventually I realized if I tapped on or flexed the tmax2 piston tank control board I could make it start and stop working. I loosened all the screws holding the board down and it worked the rest of the day. I suspect a bad solder joint to one of the relays but haven't looked yet.

With the tmax2 cooperating and accepting a small amount of leaking I ran the boat for a couple hours and in general It is a great running boat. With separate control of the two propellers it can turn around in its own length even when submerged, not realistic of course but useful for a model.

I eventually filmed a little bit with a go pro type camera and that is where I ran into the clearly self imposed problem number 3)

Jason.

[He Who Shall Not Be Named]

I ran my recently completed Engel VIIc for the first time (other than in the test pool) yesterday and had some interesting pros and cons.

Number 1) it has developed a leak somewhere in the stern bulkhead area that wasn't there when I checked a couple days before and will require me to take it pretty far back apart to find. One real downside of this model is when the two 750ml piston tanks fill with water it puts a significant amount of air pressure in the hull. All the seals need to be absolutely tip-top.

Number 2) My first time putting it in the water the rear piston tank would not move (fill with water). Every time I opened it up to check it worked fine, eventually I realized if I tapped on or flexed the tmax2 piston tank control board I could make it start and stop working. I loosened all the screws holding the board down and it worked the rest of the day. I suspect a bad solder joint to one of the relays but haven't looked yet.

With the tmax2 cooperating and accepting a small amount of leaking I ran the boat for a couple hours and in general It is a great running boat. With separate control of the two propellers it can turn around in its own length even when submerged, not realistic of course but useful for a model.

I eventually filmed a little bit with a go pro type camera and that is where I ran into the clearly self imposed problem number 3)

Jason.

Excellent footage. Loved the oop's drop at the end. And a fine sense of humor on display in the editing room.

David

[Subculture]

Use the old gas fitters trick, bit of dishwasging liquid in a cup of water and brush it around the suspected areas, then run the tanks to dive to pressurise the (not so) wtc and you should see where the breach is soon enough.

[Schmitty1944]

Thank you David for the kind remarks. I did have to swim for the camera but at least I was able to find it.

Good tip on using washing up liquid to help find leaks. I have a pretty good idea what is the cause and it's not going to be an easy fix. At first glance it appears to leak from the main big o-ring seal where the stern bulkhead fits into the polycarbonate tube. On close inspection the rear bulkhead is made of several layers of thick styrene plastic that are pre-built/bonded by Engel. I'm fairly certain it's leaking between one of those layers so that would mean finding a way to wick in solvent/glue or cracking it apart to re-bond the whole surface which would be a high risk of damage. Last resort would be to make an entirely new rear bulkhead.

Jason

[He Who Shall Not Be Named]

Thank you David for the kind remarks. I did have to swim for the camera but at least I was able to find it.

Good tip on using washing up liquid to help find leaks. I have a pretty good idea what is the cause and it's not going to be an easy fix. At first glance it appears to leak from the main big o-ring seal where the stern bulkhead fits into the polycarbonate tube. On close inspection the rear bulkhead is made of several layers of thick styrene plastic that are pre-built/bonded by Engel. I'm fairly certain it's leaking between one of those layers so that would mean finding a way to wick in solvent/glue or cracking it apart to re-bond the whole surface which would be a high risk of damage. Last resort would be to make an entirely new rear bulkhead.

Jason

If it's a delamination problem here's what you do: drill 1/8" holes, about 1/4" apart over the bad portions of hull; place masking tape on the inside, blocking the holes within; syringe catalyzed epoxy laminating resin in the holes and leave to cure; pull the masking tape and abrade away any excess resin. Done. You're welcome.

[Subculture]

I'm pretty sure they use PVC sheet for the tech rack and buklheads rather than polystyrene.

[Das Boot]

Don’t be so hard on yourself. Excellent.