mikef18

I was given an old Dumas 54" Scarab with an OPS 15cc nitro and started searching for info on it. Well I came across a thread in the gas boat section of someone doing a KAAMA build and decided to do one with the nitro engine. The main reason I decided to copy the build is because there was already a decal kit available online for the KAAMA boat to fit the 54" hull. I stripped everything out of the boat and got right to work on making a new hatch cover that matched the real race boat. It's just a little over half the weight of the original hatch, let me know what you think. I ordered all new hardware and will be sanding and sealing the hull & hatch next. I filled about 30 holes in the hull to get it back to a fresh start.

Blackout

Looks great!

martno1fan

Nice work Mike .
Mart

mikef18

Made the bow rail tonight, used brass rod and flat stock for the brackets. Tried to match the look of the real boat. Sanded off the old stripes too.

sticktickler

Mike,
Well done looks great you certainly seem a lot more motivated than others who have the KAAMA graphics. I may actually get to see how they look on a Scarab hull before I kick the bucket lol. I'm not sure how you calculated the flag is too large but in all honesty this not my first rodeo I been at this for many years. That being said I took a closer look at the flag and it is to scale with the full size (SEE PIC) as they where vectorized along with the others with care by hand from the vintage race boat photos. If however you want the flag smaller for whatever reason simply use the PDF file and print them on vinyl sheet found online. Or try a local sign shop to print the PDF as I only have a vinyl cutter and cannot cut the flag any smaller. Keep up the great work I will be watching the build closely let me know if I can be of further help.

sticktickler

Us flag history: Some may wish to know why the US flag is backwards on the boat hull above. You may notice the flag is in two directions one for the left side and one for the right side. There is a great deal of US flag edicts, most of which can be found via Wikipedia. But this one comes from an early independence battle field charge under Gorge Washington. He was empowered by the star spangled banner flowing in the wind from the charging flag carrier. If you stood on the left of the charging flag carrier it would look accurate blue field on the left. If you are on the right of the charging flag carrier the blue field would be on the right as it flows from the mast appearing backwards. In honor of this the proper edict is that if a flag is applied to anything that moves forward it must have a backward flag on its right side. This is seen on the tail of Air Force One and the modern Solder’s uniform right shoulder flag insignia.

advanced builder

Mike Good job on the build. what's that in the background ? 36-F I have a buddy that runs them. Up in Michigan He posted some video's on U-tube, let me see if I can find his stuff.

mikef18

Thanks, that's my C - hydro, I built it from a kit.

advanced builder

Now your talking. Mike
What kinda speeds? A kit, now I wish I was 20 years younger. We do get a Syracuse HydroFest in the summer. Not the unlimited hulls 1/2 scale I 'd say The C-hydro's used to run here, been a few years on them.
Gotta be fun Neil

mikef18

it runs between 65 & 70, like a go-kart on water. fun on the turns!

advanced builder

Here you go Mike , http://www.offshoreelectrics.com/products.php?cat=21
just one of the sites for drivers. We have more.

mikef18

Got it primed today, I'll start adding the hardware tonight. Still waiting for my radio box and turn fins to arrive. Anyone know what balance point to set it up on? Should I just set it at about 28 - 30% and is that with or without fuel?

advanced builder

the pic is old but still the same CoG ready to run . A few degrees off is still OK

mikef18

thanks AB, waiting on some parts before I can set up the CoG. I looked into adding scale drivers but not sure if I will. I set up the bolster seats so I can later if I want. Does the driveshaft tube need to bend up above the waterline of the boat when its at rest in the water so that the boat doesn't fill up. This would require that the engine is mounted higher as well which raises the CoG.

advanced builder

No, the lower you can mount your engine the better. The bend in the brass tube should be 1/2 way from coupler to strut. Leaving the hull at the same 1/2 way mark You will need to angle your motor mount at the mark you just put inside the hull. I have a long drill bit that I put inside my coupler to get the right angle and distance of your motor mount. How do we test?? put your cable in a hand drill and the other end in the strut , what happens when you lower the strut? she stays on course @ the 1/2 way mark. A gas driveline is different. leaving the hull closer to the engine. The 1/4" cable is stiffer than a .187 cable. You may want to go with a 1/4 "cable. Your 15cc OPS are being replaced with Gas engines. Why Cost Them big ones love nitro. I can go threw a 1/2 gal of nitro in a afternoon of running. The cost of glow plugs are high as well. $ 1 -2 dollars for a glow plug before. A short pipe can suck out the heating element out of that plug in 1 run. They can twist up a /187 dia cable like spaghetti I have 2 .67 setting just got my new 260 PUM Zenoah a few months ago. From here
http://www.gizmomotors.com/index.php...hk=1&Itemid=56

FlogginHarvey

WOW man!!! NICE work!!! That hatch looks awesome! I wish I would have had you to build mine!!! SERIOUSLY!

The seating section: can you build a second one of these??? That is the area I have been procrastinating on the MOST.

mikef18

Thanks, the hatch is a little out of true proportion because the hull isn't really to scale so I had to adjust it to what I thought looked good. I drew it out on AutoCad and went from there just cutting wood to match the drawing as close as possible. I had the original hatch cover and thought about working with that but it just seemed easier to start fresh. What is your center of gravity set at? Your hull looks like it rides nice where you have it set.

ab - I'm using all 1/4" surface drive hardware similar to FlogginHarvey's build in the gas forum. I figured I could always change over to a gas engine if I wanted. The ony issue I see right now is that the engine has to be back further than it originally was to get the 29% CoG and it effects the room I have for the pipe. I'm thinking of making an "s" header to keep the pipe inside the boat. Hopfully the header won't be too long and hurt the performance too much.

I'm also working on a decal for the dashboard, I made it on cad and will try printing it on vinyl.

advanced builder

Just the one brass bend inside the hull you'll be fine. An old rule was to have your flywheel coupler at the 29% to 33 1/3 % for CoG . nice job so far. Think about getting air inside for the carb. Also a engine/pipe can get very hot inside. Even with water cooling the head/ pipe. proper air flow is important. Just one more little tip. I 've seen guys adding bags of steel shot under the engine ,in rough water, running.

mikef18

Thanks for the tips, I'll be wrapping the header & pipe with the heat wrap and the engine hatches have big openings in the front & rear. I'll test it out and add openings up front if needed.

mikef18

Is it crazy to run an outboard pipe on this thing? I ran it on the bench right off the header and it seemed to work well. I use this pipe on my K&B 16.4 cc outboard and it rips. I would just have to add a 'u' shaped header to send it out the back of the boat. Any problems you see with this set-up? It would fit nice.

advanced builder

Mike I'm not sure on that setup. The Cooper muffled pipe. Is the kind you need. http://www.cooperpipes.com/index.html
Sound will be a factor. That baby's gotta be loud .Where you run is it near residential, you don't need to be kicked off the pond, for a loud engine. If your out in the country, you may be OK on private land

Blackout

Neat idea!

What would be the length from glow plug to expansion chamber center with the U-shaped header? If it's too long, performance will suffer. I think the .90 engines run around 12.5" - 13.5", but you would need to double check for sure.

mikef18

The length would be right at 12" with the header and yes they are loud but I run in a park that has an rc pond and never had any trouble with the noise. Cooper says 10" to 12.5" for the 90. To get the CoG at the right spot the engine is back too far to fit a straight pipe inside the boat and I would need a long 's' header to make it work which would put it at about 15". I may try this and see how it runs, I could always add a muffler later.

Blackout

Sounds like you are good to go. Should work fine.

Have you thought about how you are going to fab up the U-shaped header? I think I saw a header for a RIO 51 at my LHS with a U-shape in it. Just cut the part that you need. I think it was selling for $19.99. Might work, might not....

mikef18

I ordered a gas boat header today that I can cut to fit, still waiting for some parts to get here before I can go any further.