java230

EDIT: Changed the title since I bought it and its more of a build now.

Anyone have an ID of this hull? ~36x24 Kinda looks like a Dumas swamp buggy hull with a single rudder.

Downsides to s single rudder vs a dual?



I'm picking it up this afternoon I think

1QwkSport2.5r

It's probably a Dumas Windy.

java230

I thought it was way too big to be a windy... He said its about 36x24, with a .75 nitro on it.

1QwkSport2.5r

I didn't catch your dimensions. That's a lot bigger than a big swamp buggy. I have a BSB and its like 18x31 or so. The picture you show does look like a BSB - if it's a tunnel hull then it probably is a BSB or built from BSB plans and scaled up.

A single rudder can can be as effective as a dual rudder if it's large enough though I feel dual rudders allow more accurate steering. Bear in mind air rudders are nowhere near as precise as a wet rudder when running on water.

java230

cool, he said roughly so who knows. Im off to get it this afternoon. Ill put some more pics up when I have it

1QwkSport2.5r

Sounds good. Looking forward to those pics.

java230

Here she be!
21x36, definitely dumas style. tunnel hull, single rudder, tower hobbies .75 motor. It Idles great, mid range is good, bogs and dies in upper RPM's.... Ideas? Gas is 1 year old.




Trim tabs





Built in 06 maybe?



Came with servos

1QwkSport2.5r

Top end is LEAN. Open needle one turn, restart, and set main needle for peak revs then back off around 400-600rpm rich. Use a tach if you're not familiar with the pinch test.

java230

Did some reading and I think it was rich at WOT, lots of extra smoke before it died.

I reset the HSN to factory break in, 4.5 turns out, then leaned it out till it seemed to run right... No tach or anything. But it scoots on my lawn pretty good, enough to hit the fence and nick the end of the prop....

Stickers off. The pulled some of the yellow off with them...


First coat of oil base primer on the pulled off spots.


Light coat on the top.


Bottom will stay mostly yellow, i may do some black where the yellow is worn through.

EDIT: It did want to start backwards a lot once warm, not sure exactly what that means.

1QwkSport2.5r

Backwards starting usually indicates it's overprimed or your technique of flipping the prop needs a little adjustment. Not normally a big deal. If you lower the throttle a teeny bit at a time, sometimes the engine will slow enough and "right" itself and switch directions. As for the dying at high RPM - usually an engine will not quit at high RPM (WOT) unless the mixture is too lean, or the glow plug is on its way out. Usually bad fuel causes poor idling and throttle transition and that's only really due to water absorbtion. Gotta suck up a lot of water to make the fuel go bad.

java230

OK, I think I have it running well now. It was really rich, lots of smoke at mid throttle, then bog and die at high, reset to factory 4.5 turns and leaned out from there. Ill have to find my temp gun and check head temp.

It got a couple of coats of silver on the deck last night

1QwkSport2.5r

Don't bother with the thermometer. Tune the engine to peak RPM then back off about 400rpm and tune the idle needle for a good low idle and clean transition. Whatever the engine runs at when tuned properly is the temp the engine runs at.

java230

Thanks for the feedback. I figured it would be an easy to watch for running lean, I don't have a tach.

1QwkSport2.5r

Use the pinch test to set your needle then. Lean your needle, give the engine a few seconds to stabilize and give the fuel line a quick pinch and note the tone of the engine when you pinch. If RPM goes up, it's rich. If RPM stays the same, it's peaked. If RPM goes down or cuts out momentarily, it's lean. Basically just set it so there is a slight rise in rpm when you pinch the line. Also, ignore the smoke level or color - some fuels smoke more or less than others and the oils/additives can give a different color. Just set it a little rich and you're good to go.

java230

Exactly what I did, its set to just a tiny rise at the moment. I found a tach app for my phone, we will see if it works, didn't on my truck...

java230

Silver paint on, unfortunately I just used what I had laying around... not fuel safe... Ill have to redo it sooner rather than later....

But man it screams once tuned! moves though long grass like its nothing. Not small lake friendly...






Now antenna is only ~5" long, is that enough for longer range, so far its fine but its just in my yard. Its fast enough I will need some serious range.

1QwkSport2.5r

What kind of radio are you using? AM, FM, 2.4ghz?

java230

Its a 72 MHz 6ch Airplane radio

1QwkSport2.5r

When you run on water you're gonna want a longer antenna. I leave nothing to chance with airboats - (all of my radios I use in my boats are mostly 2.4 surface/marine or one FM synthesized) use as much antenna as you can. Add wire to your antenna wire if it's really short - solder/shrink tubing. I use mostly Spektrum marine 2.4 receivers which have two antennas (redundancy) one is long and one is short. I run the long one up the tube as far as I can. You don't want an airboat running away from you unless you have a really good insurance policy. If someone gets injured from your boat, you can get sued. Use a failsafe if you don't intend to convert to 2.4GHs.

java230

The wire is long, 16-18", tube was short. Ill add it on longer then.

Is it an issue using an older 72MHz radio? I had it, and am trying to keep costs to a minimum. I don't want a runaway, especially since the older radio will just keep it as last setting when it runs out of range.... WOT across a lake is bad. Failsafe you would recommend on a budget?

1QwkSport2.5r

Just get a longer tube - the tubes they sell for RC cars are usually 12-18" long and are cheap. As for failsafes - check out what's available for RC cars. They connect between the receiver and servos. I don't think they're that expensive - I highly recommend not buying a used one. I did and it shorted out and made one of my 1/8 scale monster trucks have a runaway - it flew off a river bluff and landed 50' below in a foot of water. It was a venom unit. Had it been new, it probably would not have failed given how I care for my electronics.

java230

Cool, Failsafe ordered. Ill pick up a longer tube. I have one that I may try to splice on for the time being. The tube thats short is epoxied to the hull.

1QwkSport2.5r

I would just break the epoxy loose and pull the old tube out and when you put a new tube on it, you can just CA glue it in if you want. A dab of CA kicker (accelerator) cures it instantly.

For ground running, you're probably okay with the antenna as-is, but on water you'll want as much antenna out as you can. The waters surface can reflect the radio signals. More of an issue with 2.4GHz, but it can happen to any radio frequency. Again - I go overboard as I don't want a runaway. Most if not all 2.4 radios have a failsafe built in, so when/if you switch to 2.4, you won't need the external failsafe.

java230

I did see that with the new radios, but its an extra expense. I had the one I am using sitting around, so il use it. Failsafe was $12 on Amazon. A lot cheaper than a new radio, the one I have is nice, just old.

java230

Well took it to the water today. It ran awesome! Turned way better than I expected. About 6' circle. No porpoising at all. Ran a full tank though it.

Bank of the river was gravel, took its toll on the bottom, will need some paint....