First Build ---- Redtail Kneeler Hydro

[siberianhusky]

Looks great! Going to have to get rolling on mine, I'll send you the plans so you can check out the design. The bulkheads and stringers are all done so I can start building, but I'm working on the side and top views, wish I has some 3d software.
Will be interesting, this will be my first "design" I hope it works out.
They are "spec" powered kneelers. We each have a few different motors, so we'll be able to test from blue can SV motors to UL-1.
John has a REK lower, I have a cut down K&B.
Still going to build the O'Berto as a friend for my Pak? Or is a rigger up next?
Cheers

[johnmaclean]

Mark, the O'berto might be next winter unless I suddenly come into a bucket of cash. Kendt pruchased some laser cut stuff for his firefighter rigger. I've been in touch with Kevin re: costing the O'berto. Looks reasonable enough. I might get im to do a set of each and just get the hulls completed this winter. Then as funds become available I'll look to power it.

Doug, the hull is 34,3/4 inches long. Beam is about 15, 1/4. Boating on a budget so I'm keeping everything I build 4s. Already have the bats, charger etc. Like siberian said. . . I'm gonna use some of my stock Aquacraft motors. . . . blue can and UL-1. The ESC will be Turnigy marine 120.

[Doug Smock]

There was some talk about these on IW a week or so ago. They are interesting.

Keep up the good work!!
Doug

[siberianhusky]

The certainly are something different, thats for sure! Don't think it's a boat that will respond well to massive power and a heavy throttle finger. Everything I've been able to find about them claims they are a real drivers boat.
We'll have three of them running next year. Going to be fun!

[johnmaclean]

Okay, back at it for a little while today. I am at a stage where I spend more time gathering information than actually building. . . but it is one of the most interesting aspects of the hobby. I want to get some of this information nailed down so I can determine location of compartments for servo, ESC and batteries. I've temporarily located and mounted the REK unit and motor on the transom . . .

Particularly I was researching the how-to's of establishing the centre of gravity for a hydro. Is this a hydro in the formal sense of the word or a cross between a tunnel and a hydro? Is the cg established by measuring from the transom forward or from the rear edge of the ride pads at the stern of the boat? Makes quite a difference on the placement of the batteries.

I'd like to hear arguments, pros and cons of locating the servo either close to the motor or at the other end of the cockpit. I think I've seen pics of both in tunnel hulls. The servo is currently placed in a makeshift compartment in the last third of the cockpit.

[kendt]

I think mounting it up fron is only done for balancing purpose. No point doing it if you dont have to or you'll have honkin long cables running to the motor and they will be in your way inside the hull.

[siberianhusky]

They are running the cg pretty far back on these. The turn fin is also mounted farther back than a normal hydro. I'm aiming for as much adjustability as possible and lots of testing. There are a few nitro ones running and us trying the electrics. We're in sort of experimental territory.

[johnmaclean]

I've temporarily set the cg at 8, 3/4 inches (25% of total length of the hull) ahead of the transom. I originally expected that the battery compartment would be well forward in the cockpit, perhaps under the driver but at 25% cg they are currently sitting just ahead of the servo which is in the rear third of the hull. Not gonna make anything permanent just yet though.

[kendt]

Not sure where you got that number john but i dont think its right. I believe it should be more like 10"from the transom.

[johnmaclean]

20111230_0001.jpg
Finally getting back to posting some pics of the build. In preparation for setting up the cg I mounted the REK lower unit on the transom with attached 3674 motor I bought over the holiday. Decided to add a 1/8 plate the size of the outboard mount on the interior wall of the transom.

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I drilled and tapped the plate so as to avoid the hassle of getting too large of fingers in too tight of a spot in order to make any final adjustments to the depth of the prop later on. If my pockets were deep enough I would probably look at acquiring something like a Hijack mount to make that process easier.

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The cg is now set at 30% and a fair bit of time was spent deciding on a home placements for each of the components. Lots of trial and error using a piece of 3/4 pvc pipe as a fulcrum.

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[johnmaclean]

The batteries, ESC and receiver will be installed in the forward compartment while the servo is located in the next compartment back. I had toyed with the idea of having only two lexan hatches to remove for servicing. The motor leads and cooling lines would have emerged through small panel just ahead of the mtor. But now I have decided on a third removeable lexan panel just ahead of the motor where my motor leads will emerge. It will allow me better access to the area when the need arises as well as an opportunity to do a visible inspection. . . Well at leats that's the theory. . .

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As a maintenance electrician I am forever cussing the engineers and construction guys for laying out a job in a way that makes access to components very difficult for those of us who are left to maintain the equiment down the road. So the rear compartment will have two lids, the rear one probably being removed on rare occasions.

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Since the driver will be attached to the forward hatch in a semi-prone position, using velco strips, I'm thinking of making that hatch out of wood.

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Servo shelf supports and ESC shelf have been installed along with a bulkhead dividing the forward and aft compartments as well as the framing for the compartments. Everything is ready to be sealed now. The male half of 5.5mm bullets will eventually be epoxied into that bulkhead to connect the ESC with the motor leads.[ATTACH=CONFIG]68045

[johnmaclean]

With the exception of the transom the hull is now sealed with epoxy. The boat will be painted so the next step is sanding and priming. I'll probably paint the entire hull white and leave it that way until I've actually water tested the set up.

I have a number of issues to work through including:

The REK lower unit doesn't have any provisions for water pick up that I can see. I've seen some lower units that appear to have had pick ups added to them either by drilling through the end of the cavitation plate or mounted on top of the plate and extending over the end of it. Being my first outboard and first build I am more than open to suggestions.

Need to fabricate a steering arm to attach to the conversion plate. I'm considering making up a wafer that will match the complete foot print of the conversion unit and be sandwiched between it and the lower unit. I've searced for REK accessories and the closest match I could find was on the Fullers Fast Electric site.

[kendt]

Its coming along well. All thats needed for the water pickup is a fitting with a lock nut behind the prop. You can use a splitter to route the water to the motor/esc.

[johnmaclean]

Thanks, Ken. I thought I saw at least one outboard set up that looked like it was using a splitter for the cooling lines. Some others seemed to have the conventional set up that routes the cooling water through the ESC and then the motor. I'm not clear about the water pick up dsecription. Is the fitting epoxied the top of the cavitation plate with a brass tube running through it just behind the prop?

Think I'll take a trip to the Home Depot today and pick up some lexan for the hatch sections and then to the LHS for a sheet of plywood for the rigger I want to start next week.

How is your kneeler coming along?

[kendt]

The fitting just goes through the plate with a nut on the other side to hold it in place. No epoxy needed. Personally i would never share a water line between motor and esc. In the summer when the water is already 70 deg your not getting optimum cooling as it is.