New Builder: DYMotorshop 750mm Mono - High Deep V "Jack"... watch me learn!

[Jesse J]

A few thoughts looking at your mock up:
1) what depth do you have the center line of your strut? Recommend 1/4-3/16 inch above keel.
2) I believe in keeping center of mass as compact as possible (not spreading out the motor, esc, batts too much.

[autolex]

Center line of where the shaft goes through? I will measure it...

[autolex]

So I made a little bit of progress today/yesterday.

I filled the nose with approx 1oz epoxy with chopped CF for additional durability.

In addition: I cut a transom doubler and epoxied it in as well.

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After this setup I started attacking the hatch bolts. I've used this method for at least 15 years when securing things to fiberglass (I ran a car stereo shop in college, I cannot tell you how many brain cells I killed doing custom fiberglass work).

The basics are: bridge the corner, put it in compression (not shear in any way), tack with cyanoacrylate, then cover it with epoxy for a permanent mount. (I'll do the epoxy when I cut my deck support ring this week)

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As you can see it gets the threaded inserts almost all the way to the corners of the hatch.

To keep this from breaking, after I drill the hole I usually glue a thin washer on either side of the fiberglass/CF and put a piece of aquarium tubing on the threads as a "bumper" to help dampen the torque/bumps.

[autolex]

(5 image limit)

A few more pictures for illustrations sake.

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Just trying to show the thread path here with these ^^^

Next steps: Cut the CF ring for the deck support (copying something i saw on fweasels outerlimits build) and actually measure out everything for the stern mockup.

Any guidance on offsetting the driveline to the side a few mm to combat torque roll? I saw Jesse saying i should do 1/4-3/16" above keel for the driveline centerline, that seems doable.

[autolex]

Well my wife went and fell asleep with our 4 year old while rocking her to sleep...

So I went ahead and drilled the hatch bolt holes. Will clean these holes up and epoxy some stainless washers to the top side tomorrow.

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[autolex]

I went ahead and epoxied the corner trusses in and put some gasket around the lid and put some fuel hose on the threads of the hatch bolts to keep them attached.

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Time to start figuring out the driveline and motor placement.

[Jesse J]

Torque roll: I deal with it by offsetting batteries a little to port side. It will be less noticeable with smaller props, so I like adjustability.

[autolex]

Figured out the layout and mounted my motor mount and ESC mount in the hull (as low as was possible).

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This should make the flex shaft/stuffing tube quite short (7"-ish flex) but should be the best for weight distribution.

On to figuring out stinger placement so I can figure out stuffing tube mount and length.

[autolex]

Drilled the (first) big scary hole in the hull today.

I cut some brass tube to length after I was happy with the bend and the alignment with the coupler (shoved an old piece of flex in the coupler to ensure concentricity).

Tacked it in place with hot glue so I can remove the motor and fit the carbon flex tube support and seal the entry on the stern.

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Took Jesse's advice and drilled the centerline/flex tube hole centered just over 0.25", the TFL stinger I have is fully adjustable so this should end up perfect.

Next: on to mounting and locating of stern hardware and cutting the deck support and epoxying it in.

[Dirk Jan]

Nice hull autolex! If you want to use a GPS, you will need a non-carbon fibre hatch part, because the GPS signal will not go through carbon fibre.
Looking forward for the updates.

By the way: I use the SSS3674 1650kV on 6S for my tunnel hull. It spins a 43mm prop with ease. Very happy with the performance!

[autolex]

Nice hull autolex! If you want to use a GPS, you will need a non-carbon fibre hatch part, because the GPS signal will not go through carbon fibre.
Looking forward for the updates.

By the way: I use the SSS3674 1650kV on 6S for my tunnel hull. It spins a 43mm prop with ease. Very happy with the performance!

Thanks Dirk! I plan on putting a 1/4"-20 (camera) thread T nut on the hatch for mounting things like go-pro or GPS, I appreciate the reminder to do this!

[autolex]

I cut my deck support ring and epoxied it in (in three different pours, only way to get it to stay where I wanted)

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Cut a Flex tube support and epoxied it in too.

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Going to attempt my inlay tomorrow, i somehow managed to guess the weave and weight that DYMotorshop uses nearly exactly!

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How do I setup these battery trays I bought?

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There's 4 super thin ovals that came with the trays, do i just glue them to one side as a spacer/"legs"?

Thanks in advance, you all have been so helpful!

[fweasel]

The tabs get glued to the bottom of the tray to act like spacers so that you can still pass velcro straps underneath them. Rough up the mating surfaces to get better adhesion.

I made and installed a deck support nearly identical to that for my SV43 hull. I tacked it in place with CA, ran CF tape across the back edges, them used thickened epoxy along the front seams. Using cloth on the back sides helps prevent the epoxy from running underneath the brace, and thickening the mixture lets you glue more seams at once without it sagging in directions you don't want it to go. I left a weep hole at the bottom near the keel to let water drain out more easily if it got past the brace.

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[autolex]

The tabs get glued to the bottom of the tray to act like spacers so that you can still pass velcro straps underneath them. Rough up the mating surfaces to get better adhesion.

I made and installed a deck support nearly identical to that for my SV43 hull. I tacked it in place with CA, ran CF tape across the back edges, them used thickened epoxy along the front seams. Using cloth on the back sides helps prevent the epoxy from running underneath the brace, and thickening the mixture lets you glue more seams at once without it sagging in directions you don't want it to go. I left a weep hole at the bottom near the keel to let water drain out more easily if it got past the brace.

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Thanks Fweasel! Your build has been an inspiration for me, so the deck support is exactly what i was trying to copy.

I plan on drilling a weep hole once the epoxy has been cured for a few days (I plan on putting some 2lb foam in front of the support for floatation)

I will be doing something similar to your CF tape: I plan on wrapping my inlay down over the bottom and sides of the support.

where are you getting your thickening agent? is it just chopped CF? CF powder?

[fweasel]

I thicken West System G-Flex epoxy with their 406 Silica powder. You can get to to peanut butter consistency if you add enough.

I'm not sure if I understand how your inlay will interface with the deck brace. If the inlay is going to wrap up the front face and across the sides, be sure to cut the appropriate relief notches in your paper template so that it lays flat on the brace and doesn't buch up in the corners. It will lay flatter, be stronger, and more importantly, look cleaner.