Later-Model Dumas Scarab 38KV > AVS Build

[Mike W]

Yes, funny how I fell into HOTMBC right after you left. What a club! And definitely the largest reason I'm hooked on boats again. Thanks so much Jim!

No nats for me and still bummed I missed Dallas. Maybe next year. LOTO is the big event planned for this year!

Underside filler work and blueprinting is complete, and the top is all blocked and filled 80-150. Just a few filler touchups remain before a final sanding with 320 including the edges then it gets primed.

[Mike W]

Wasn't happy with the step alignment. Almost lost my mind trying to make sense of the step angle-of-attack, offset, etc. and the two steps being different lengths didn't help much. The hull bottom also reduced deadrise as it approached the transom. Lots of straightedge checks, measuring, and eyeballing! I try not to think about how much time I have into this hull mod but it is finally ready for primer and the decals are ordered. Definitely cannot recommend this mod.

[stac1627]

Hey Mike,
Thats gonna be cool!!
What does the empty hull weigh?

[Alfa Spirit]

This DUMAS Cigarette is very nice, I like how you modified the powertrim drives.
The steps are not scaled but this is not a problem. I hope those mods won' t affect the efficiency of this boat on the water.

Who will reissue a 1m or 1,20m Cigarette hull?

What do you think about the inexpensive Rocket Motors?

[Mike W]

I’ll weigh it when I get a chance. The bodyworked areas were primed with Featherfill and blocked out to 320. The entire hull will be primed in 2K next then off to a body shop for paint.

The steps are larger and deeper, as well as set back a little farther on the hull but these changes seemed suitable for the model boat at model speeds. Less of the boat is in the water?

The Rockets look good we’ll see how they run in a few weeks! I decided to make the drives steerable and a few parts are being machined now to make that happen. Hopefully the turn radius will be tight enough.

[Jesse J]

I am super interested in these drives! Do you have a list of parts and how you modified them?
Can’t wait to see/ hear how the boat runs.

[Mike W]

I am super interested in these drives! Do you have a list of parts and how you modified them?
Can’t wait to see/ hear how the boat runs.

Well it started with a HOTRC servo mount I found for another build. The name fit so well with HOTMBC I decided to see what else they offered.

Any cat drives with rear pedestal mounts will work. Discard the rear pedestals and replace them with some modified car shocks mounted to the transom and they work on a V hull with an offshore racing look. I used some similar to these, removed the shaft and replaced it with a Ti turnbuckle, and left-threaded an aluminum dowel plug inside the shock body. The location of this plug will be fixed with epoxy once the drives are finally mounted and the desired adjustment range is determined.

https://www.ebay.com/itm/Hot-Racing-TD120T01-Black-Internal-Spring-Air-Shocks-120mm/132738122099?epid=1336782172&hash=item1ee7cf0173:g:48oAAOSw5qdb5Olh

For upper mounts my original plan was to notch these in the center to mount the shocks.

https://www.ebay.com/itm/Hot-Racing-Arrma-1-8-Rear-brace-and-wing-mount-AON12WM01/273630153438?epid=3027483129&hash=item3fb5a0cade:g:80oAAOSwq6VcJo8t:sc:USPSFirstClass!78641!US!-1

These ball links mount to the bottom of the Ti turnbuckles and couple them to the drives at the pedestal mount location.

https://www.ebay.com/itm/Hot-Racing-ERVT154X01-Ball-Type-Aluminum-Shock-Ends/123438393319?epid=3024401566&hash=item1cbd8067e7:g:u~0AAOSwo3BbykiD

Before I decided to try to make them steerable they needed to be locked together parallel so this spacer was the right length.

https://www.ebay.com/itm/Hot-Racing-Axial-AX10-SCX10-6-x-58mm-Aluminum-Links-RCL65801/273593031429?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

[Mike W]

Finished up two LOTO cat bottoms and got all the boats primed today. 👏🏻
Jeremy Moore is cutting some steering ram mounts and drive angle brackets to allow the rams to mount and the drives to be coupled with ball joint tie rods now instead of solid standoffs.

Nice to have the hull sealed up in its last coat of primer so all the remaing assembly can be completed inside!

[Mike W]

I thought I had lost the engine cover. It was in the pantry under a large jar of marinara because it was so concave. Some improvement but still not flat. I beadblasted the bottom to clean it up for adhesion, ground quite a bit away on the backside to smooth it for a layer of CF. And glassed in a chunk of foam for more strength and flotation.

[Mike W]

When this cures I’ll flatten the top and bond on a pair of Sniper 45 supercharger scoops.

[Mike W]

Scoops and decals came in. I need to finish this hatch so I can get this painted next week but it pains me some to destroy the nicely done louvers. 🥴

[fweasel]

Coming along. I think the finished scoops will make you forget all about the louvers!

[Mike W]

Hey Mike,
Thats gonna be cool!!
What does the empty hull weigh?

I weighed it today. With engine cover and all my formers inside it weighs just under 8.5 lbs. I'm using a flat cockpit cover initially that will add more weight, and if the boat proves itself I'll build a scale cockpit this winter.

[Alfa Spirit]

You won' t glue those scoops, right ?

[Mike W]

You won' t glue those scoops, right ?

Oh yes. They'll be blended right in. Why not? They might be ripped off in a flip?