Madcap

[lftmx3]

Well it's finally almost time to see if this thing works... Being that I had never built a boat before let alone a race boat, I'd appreciate if you guys could point out any potential issues before I try to take it out. Still waiting on the state gov. to issue me a VIN so I can register... One question I do have is how many turns should the wheel take lock to lock? right now it seems the cable wants to double over on the drum for the last 1/4 turn in either direction. I don't want to risk the cable riding off the hub. How often would I realistically need to angle the motor that far to one side? Thanks!



IMG_0393.JPG

IMG_0397.JPG


IMG_0395.JPG

[Guest]

Boat looks good!
Normally in a PRO Hydro or Runabout you wouldn't turn the wheel any more than a half turn.

[dwhitford]

I agree. I have my PRO hydro set up with indirect steering (pulleys on the steering bar) to turn left with 1-1/4 turns, and right with only 1 full turn, more in either direction than necessary except for idling back into the pits.

[trident]

Be sure to tie that motor down, across the driveshaft housing exhaust snout. Otherwise the motor will kick up as you slow down, then you lose steering control... and may break things. I like 3 wraps of 5/16" Nylon line, turn the motor when you tie down, then it tightens when you straighten out.

[jeff55v]

Nice looking boat.
You're steering is gonna be very slow. You have a small hub steering wheel, indirect steering, and a very long steering bar. Those three things will combine to make very many turns of the wheel to go from lock to lock.

[mercsami]

I think your steering cables are cut too short,I don't see any cable clamps. You should have 2 clamps on each cable. Your cable anchors or "tie backs" are not designed to hold all the cable tension.

[ZUL8TR]

You might consider direct cable steer set up as a trial after you try the way you have it. No cutting to try just disconnect from the tie back and lock the cable after the pulley with 2 clamps on each side of the steering bar (safety like mercsami notes) and some double wraps to temporary deal with the excess. With that big steering bar it just might turn like you want with less wheel rotation (1/4 to 1/2) ? Will be a bit harder to turn the wheel since the 2:1 mechanical pulley advantage is gone. You need the correct tension on the steering cable and really only 2 wraps around the wheel drum since excess cable there only fowls up the operation smoothness and could cross tangle. Be careful and wear a good jacket and helmet and have a safety boat near by.

[lftmx3]

Yes I think I'm going to make another steering bar with shorter arms raked a little more inboard. I was afraid the steering response setup as-is would be too slow but didn't want to face the music. I'll probably go with a direct setup, I tried it out and it doesn't seem like it will be too heavy for just cruising.

[mercsami]

The two cable attaching holes in the ends of your steering bar should be at the center line of the motor pivot pin.If not when you turn in either direction your cable will go slack.I was taught this on this forum,very good advise.

[Drotti]

Beautiful boat!
Did you build from full size plans? Where did you get them?
Thank you, Scott

[johnsonm50]

I'm in agreement with everything posted but want to add some insight from having done similar things. I have a Kelly Airborne 'B' that's powered up with a 31.8 ci OMC on a Bass unit. That would be similar in power to what you have. 1st, I'm guessing it's a 'D', about 13'? How far below the bottom is the prop shaft center? What you may find is a tendency to porpoise. It is to be expected till near full throttle, then it should smooth out some. It will likely cavitate on take off, you will have to lean forward [I reach out & put weight on the wheel hand & rest my gut on the wheel as far up as I can reach till the prop grabs] some will grab better than others. There are likely things to work out, it assuming the motor runs well will be fast & will take serious care to get used to. If it seems a handful remember - the throttle works both ways & the most fun will be in getting it to perform well, without pounding the hell out of it before it's set up well. Be especially careful getting used to turning at speed, 'steady on the wheel capt'. Speaking of the wheel, a 5" or 7" hub can be added to lessen the turn ratio as well as or instead of direct. Direct steering works fine but can be amusing to handle at low speed. The steering should be reasonably tight, having a loose sloppy feel during a race is not a comforting drive lol. The tie down mentioned serves that end as well as holding the lower unit tight to the transom. Direct steering works fine but can be amusing to handle at low speed. Be aware of where your throttle cable is, kinking it with your foot can cause it to stick wide open [don't ask lol].
The idea being great fun, I wish you the best. It's a fine craft. Madcaps are said to be Kelly's best design. Last but important, as you test run it bring a notepad & write down what you experience. If you need to change things change one at a time with notes. That way you will know what works instead of guessing what of 3 things. Once it's riding well & you go for potential speed you'll need a way to document MPH & RPM & use the notes kept to make better informed choices as you progress. Good Luck & keep posting.

[lftmx3]

Drotti, the plans can be found at boatsport.org/kelly.html. I initially planned on building a canoe then found Hal Kelly... Plans are pretty straight forward, I had only build RC aircraft prior, and the boat went together using many of the same skills (btw...buy lots of epoxy!)

johnsonm50, thanks for the advice, I wish I could find someone here in Louisville with some knowledge of these boats... yes it's 13' long. The prop shaft center is set at approx 1/4" below the trailing edge of the bottom. After replacing the stator and 1 coil I have the 402xs running pretty good in the trashcan. Pull-starting takes an effort, can only imagine how hard it will be to do while floating... and then turn around to man the controls!!

[jsilvestri]

Try to contact Dave Harkins. I don't have contact info but he raced for many years and might be able to help and lives in that area.

[ZUL8TR]

Drotti, the plans can be found at boatsport.org/kelly.html. I initially planned on building a canoe then found Hal Kelly... Plans are pretty straight forward, I had only build RC aircraft prior, and the boat went together using many of the same skills (btw...buy lots of epoxy!)

johnsonm50, thanks for the advice, I wish I could find someone here in Louisville with some knowledge of these boats... yes it's 13' long. The prop shaft center is set at approx 1/4" below the trailing edge of the bottom. After replacing the stator and 1 coil I have the 402xs running pretty good in the trashcan. Pull-starting takes an effort, can only imagine how hard it will be to do while floating... and then turn around to man the controls!!

Don't do any testing by yourself, have help starting with a boat holder in the water and have a rescue boat available. Of course wear a good race jacket, helmet and a safety mag cut off lanyard. That engine has full butterflies, right?

Take it easy till you get lots of practice just driving it, then when real testing starts as stated log in what you did one thing at a time.

[johnsonm50]

Drotti, the plans can be found at boatsport.org/kelly.html. I initially planned on building a canoe then found Hal Kelly... Plans are pretty straight forward, I had only build RC aircraft prior, and the boat went together using many of the same skills (btw...buy lots of epoxy!)

johnsonm50, thanks for the advice, I wish I could find someone here in Louisville with some knowledge of these boats... yes it's 13' long. The prop shaft center is set at approx 1/4" below the trailing edge of the bottom. After replacing the stator and 1 coil I have the 402xs running pretty good in the trashcan. Pull-starting takes an effort, can only imagine how hard it will be to do while floating... and then turn around to man the controls!!

Your welcome, I got into my Airborne gradually starting with a fishing 25 that would do 33 moved on to a 25 of more cubic inches to make 44 then added a racing lower unit & was getting 53+. That's when it was going like it was meant to, as much on air as water. By then I was familiar with what to expect & found the faster it got the better it behaved. It's also when I got serious about testing & racing.
At 1/4 below you might be too shallow for the prop to grab within reason for fun driving, D runabouts racing now are required to be at least 3/4" deep at the rear of the prop shaft & that's for closed course all out racing. I'd recommend starting out at 1 or even 1-1/4". It isn't as much about 'the higher the faster' but more about where it works best. We're allowed to run 3/4 deep in CSH but I sometimes run 13/16 to 7/8" if it's ruffed up more than just by other boats, props gotta be in to work lol. To get out 1st time I concur with Z, bring assistance, safe gear & if possible a chase boat. You will want to be sure you can start it by yourself, I do often, you should warm it up so it starts easier, & do it with the least possible throttle. It's unlikely to jump out from under you like a hot dirt bike can but can send you off balance if you're not ready.

[Yellowjacket]

If you've been running the 402 in a trash can you need to check the grease and make sure it isn't getting contaminated, as well as checking the grease in the tailcone bearings. Do a search on maintaining the "D" quicksilver lower unit and you'll see what you need to do, but after each couple of days of use or if it isn't going to be run for a week or more you'll need to be checking the grease in the lower unit and using a grease tool on the tailcone bearings. If you leave water in the tailcone or the lower unit it will make a mess of things in short order.