54" Dumas Scarab Build

[rickwess]

I picked up a Dumas Scarab yesterday. All in all it's in great shape. The orange is the original gelcoat and the black is just flat spray paint. It's never been drilled just a half a$$ attempt to install rails. There are a few small stress cracks from years of transport and storage.

It came with the hatch but it's in pretty sad shape with lots of stress cracks in the gelcoat. Not enough FG to stiffen it up


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She's a biggie:

Length: 54"
Transom Width: 14"
Transom Height: 5.75"
Weight: 4.5 kg

[rickwess]

More pics. Notice the built in skeg on the hull.

I do need a bigger workbench.

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[Savage Skidoo]

Shes a beast Rick , looking good ......easy guy to deal with . i'll be keeping an eye on your build .....cheer's

[rickwess]

First things first........pull out the rails. They were spaced at 7.5" so of no use to me. They were bond with 3M 4000 or 5000 then sprayed over with flat black paint. Two areas had had a strip of FG over it. I was able to dremel though the majority of the goop then heat it up to loosen the bond. It all came out fairly well and once i strip the paint, it'll see how much goop is left. It will have a CF inlay so I'm really just interested in getting to a point where there will be a good bond for the CF.

I only caused one small stress crack in the gel coat in the process. There was a block in wood bonded in under the windshield and again just about the transom. The windshield area has quite a bit of flex to it (there was already a stress crack close by to where I was working). I was worried about how hot the area was getting trying to loosen the block and I just applied too much force. No biggie. I know I need to repair other areas anyway.

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Just for giggles, I placed it beside the Insane Mono 34 I built over the winter.

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I'm not even worrying how to power it yet. The next steps will be to reinforce the hull and figure out how to seal the hatch opening.

[rickwess]

Question 1: Reinforce the Bow

Between the ridge on the deck and the keel, there is a natural "slot" for a bulkhead that runs lengthwise. That will take the flex out of the bow.

I'd also like to reinforce the seam and the rest of the top deck and hull with either core mat or CF. The problem is that the tip of the bow is 33" from the hatch opening. My hand/arm just can reach that far.

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Aside from asking my 5 month grandson to climb under the deck, any suggestions on how to work in that space? Would core mat be easier to work with that CF? In the end, this area will be foamed and sealed with a bulkhead so I'm not concerned about how it will look. I'm looking for strength to survive the inevitable crash.

[rickwess]

Question 2: Seal the Hatch

As you can see from the pics, the hatch is flat and the open slopes up by the windshield. Anyone know how this is supposed to work?

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[Ken_NJ]

If this is any help to you. Here is a 54" build. He made his own cockpit.

http://www.rcuniverse.com/forum/speed-rc-nitro-boats-117/10258611-dumas-54-scarab-kaama-race-boat-build.html

His finished boat. I was in contact with him, he did sell it.

http://www.performanceboats.com/other-stuff-sale/92840-54-scarab-rc-boat-kamma-replica.html

I'm building a 45" Dumas Scarab, waiting on running hardware and ply to build the cockpit.
http://forums.offshoreelectrics.com/...t-Dumas-Scarab

[TheShaughnessy]

I think that "skeg" might be where the flex was originally designed to exit the hull. Not sure why you would need a skeg there on a v hull

[rickwess]

I think that "skeg" might be where the flex was originally designed to exit the hull. Not sure why you would need a skeg there on a v hull

From the inside of the hull, it looks solid. The keel channel does not drop lower where the skeg is. If it was for that, is there a downside to running a stinger or a strut where the flex exists at the transom?

[rickwess]

If this is any help to you. Here is a 54" build. He made his own cockpit.

http://www.rcuniverse.com/forum/speed-rc-nitro-boats-117/10258611-dumas-54-scarab-kaama-race-boat-build.html

His finished boat. I was in contact with him, he did sell it.

http://www.performanceboats.com/other-stuff-sale/92840-54-scarab-rc-boat-kamma-replica.html

I'm building a 45" Dumas Scarab, waiting on running hardware and ply to build the cockpit.
http://forums.offshoreelectrics.com/...t-Dumas-Scarab

Thanks. It does help a little. On mine, the hatch opening isn't on the same level all around. The flat mounting area slopes up by the the windshield and at the front of the windsheild the flat spot is almost none existent.

[TheShaughnessy]

From the inside of the hull, it looks solid. The keel channel does not drop lower where the skeg is. If it was for that, is there a downside to running a stinger or a strut where the flex exists at the transom?

If it were me I'd remove the skeg altogether and definitely go with the more modern stinger or strut style set up. Maybe this was originally set up for a sub-surface drive?

[rickwess]

If it were me I'd remove the skeg altogether and definitely go with the more modern stinger or strut style set up. Maybe this was originally set up for a sub-surface drive?

I think they were originally designed for submerged drives. Is there a downside to just leaving the skeg there and go with a stinger or strut?

[TheShaughnessy]

Only possible thing I can think of is the boat wanting to ride up on the skeg but I doubt that would actually become an issue with the size of this one. It's drag. Also just theory here. Build it with skeg intact and go from there.

[rickwess]

Only possible thing I can think of is the boat wanting to ride up on the skeg but I doubt that would actually become an issue with the size of this one. It's drag. Also just theory here. Build it with skeg intact and go from there.

Agreed. Once the hull is fully loaded, the lift from the skeg would have little effect. At best the skeg is providing some lateral stability.

[Livewire121]

Hey Rick how's it going? I know you spoke to Mike (Savage Skidoo), but I just wanted to give you a few details about the boat meet with the Boaters And Crawlers Durham group. We have planned a season opener for May/10/14 at Frenchmans Bay. Email me if you're interested at [email protected]. I had to message you here , because I can't send or receive private messages here on Ose for some strange reason.

Cheers,

Richard