dr.peck76 1st build(Canada)

[dr.peck76]

Hey, I thought I would post some of my pictures and descriptions instead of littering other threads with my stuff. This is my first airboat build, it's 13' long over all, 5'6"at the bottom of the transom and 80" at the top. Soft chines built to a 6" radius. The hull tapers to 60"wide at the bow.
.125" floor plating, the rear 4' of the side are .125 as well with the forward sections .080". Transom is also .125" and 24" tall with a 4" center dip for prop clearance.
I Choose a 2010 Yamaha Nytro snow-machine engine for power, it is a three cylinder, four stroke, 1049cc's and dry weight is around 150lbs. This engine is from Yamaha's Genesis platform and was origionally designed as a four cylinder motorcycle engine but has found it's way into all powersports. This model is fuel injected with an aftermarket turbo set-up and produces around 200hp at 9000 rpm. Engine red-line is somewhere north of 12000 rpm.
I used the factory exhaust but had to massage it heavily due to the new turbo location, full stainless on the header. I had the pieces of the prop shaft custom machined to use 2- 1/2" pillow block bearings with a spherical roller element for axial thrust loading. Theses bearings spec out at about 1200lbs each for axial loading. The belt drive is a 36mm wide, 8mm pitch Gates timing belt.

My rigging is made from 1" by 1" by .125 wall square tubing (aluminium) with 1/8" and 1/4" gusseting. Bow deck structure is 1" by 2" by .125" tubing with the obligatory 2" aluminium pipe at the leading edge.
I've been at it for almost a year now. Holidays, kids sports and paying side jobs getting in the way of my free build time at home. This past weekend I have skinned the rudders and started on the steering linkages and my level of excitement on the project is at a new high. I've had it running twice with power to the prop, and on the dollies it pushes hard enough a man can't hold it back at about 800 prop RPM.

TO do list as of Mar 8
- complete steering linkage
-build accelerator linkage
-complete bow deck
-install UHMW to bottom of hull
-install lighting
-install bilge pump
....install the 1000 little things I haven't thought of yet....

[Corky]

That boat is awesome !! You're up on the next level with that build......With that kind of HP and RPM you HAVE to make sure all the components are up to the task and it looks like you're accomplishing it...I can't wait to hear and see your boat in action....

[dr.peck76]

After viewing your build Corky, I really appreciate your words. Thank you. I've got a few more pictures to post but I'm having trouble uploading them from my phone.

[Papee]

That boat is awesome !! You're up on the next level with that build......With that kind of HP and RPM you HAVE to make sure all the components are up to the task and it looks like you're accomplishing it...I can't wait to hear and see your boat in action....

Unfortunately the forum software will flip the photo to its widest size sometimes placing them sideways. My only suggestion for that is to take photos landscape or sideways when taking them on your phone.

[dr.peck76]

Thanks for the hint. I thought it was something I was doing.

[dr.peck76]

I got a little more done with the rudder linkage but ran into a snag with the steering handle. I measured the right amount of travel calculated from the steering arm pivot but failed to realize where in the arc of travel that distance was. I ended up with full left rudder and 0% right. Papee, I'm sure you've seen something like this before! I had a good laugh at myself, opened a beer and went back to the house. I'll build another steering lever and primary link-arm tonight. Attachment 1820Attachment 1821

P.S. it was me doing something wrong, my camera has the auto rotate feature off!! LOL

[dr.peck76]

So I've been finalizing some mechanical linkages and have got my "go pedal" finished. Last night, I asked a friend to stop in and we stripped the hull and flipped it for the poly install. There's my son in the cage "flying" it. LOL and the rigging,
and the hull. I'll finish a little welding touch ups, as I did the external seam overhead and then on with the UHMW, 1/4" thick.

[Corky]

Nice to see the boy getting involved with your project......

The local boat builder around here adds the poly to all his bottoms no matter how small the engine or hull is...His argument is the poly floats and ends up with a neutral balance between the added weight and bouyancy to the hull... As papee has pointed out it still adds mass to the overall build and could create problems for some low horsepower builds...But you're not in that category with your engine.......Now he does use stainless hardware and has a custom stop on the countersink for the perfect hole everytime...And uses a marine grade sealer with the stainless screws...

[dr.peck76]

Thanks again for the tips. I do have a countersink tool and stainless fasteners but they are self tapping. ...do you think sealant would still be required? ? I have been scratching my head on this one, and any input is valued.

[Corky]

Self tappers are fine....I'd use the sealant...There's just too many factors not to do it...The aluminum will expand and contract at a different rate than the stainless fasteners...You run the risk of the fasteners getting jarred if they take a hit and even a little movement leads to a leak...This is the stuff I'd use.. it's an adhesive/sealant and supposedly you'll ruin the fastener before it comes back out...Check out the 3m line of marine sealants there's semi-permanent and permanent sealers....

[Papee]

I don't have much experience with poly but I do know it has to be warm to put it on. It should be laid out flat in the heat to warm up then warm when putting it on.

I think you are going to be running that engine hard to move that boat along. It's a toss up for me and the poly on a lower horsepower setup. The poly does add protection but also more weight. As far as flotation it's a wash, the poly will float its own weight but there still is that weight you are adding, like hauling around an extra person all the time.

Id rather cut the bottom off and put a new one on than put poly on. That's just me though, most folks know I march to the beat of a different drummer. The key to this whole low horsepower deal is weight, you're already heavy with that hull, not that it's a bad thing,I just think running that oil burner(2 stroke) will be running hard to push that barge around.

I may be way way off on my thinking, my wife can tell you Ive been wrong a lot. I'm very interested in seeing the results of your build. It reminds me of a guy I saw at the river last year or the year before. He had a beautiful hull made by a local guy. He put fancy food up instrument panel on it, a big junction box to house all his wiring and fuses, and a few other weight hogs. He powered it with a really nice looking VW engine. The thing won't get on plane. I've never seen him on the river since, I don't know what became of his build.

[dr.peck76]

Id rather cut the bottom off and put a new one on than put poly on. That's just me though, most folks know I march to the beat of a different drummer. The key to this whole low horsepower deal is weight, you're already heavy with that hull, not that it's a bad thing,I just think running that oil burner(2 stroke) will be running hard to push that barge around.

I guess we shall see. I'm defiantly impressed with your posted weight, very light! I'm very excited as well to try my creation out, although the ice will be on our lakes for a few more weeks. HA! It's the first day of spring and I woke up to 3" of snow on the ground!! The rivers are starting to flow a bit as we have been above average for temps lately. Day time highs around 8*C...not sure what that is in *F. I thought I mentioned that my engine is a four stroke.... it is a snowmobile engine, made by Yamaha in 2010, fuel-injected four stroke

[dr.peck76]

...I'd use the sealant...There's just too many factors not to do it...The aluminum will expand and contract at a different rate than the stainless fasteners...You run the risk of the fasteners getting jarred if they take a hit and even a little movement leads to a leak...This is the stuff I'd use.. .

Very good point on the different coefficients of expansion! Thank you Corky. I'll be looking for this stuff shortly. I guess it's better to be safe than burn out a bilge pump!!

[Doozit20]

That is one bad motor right there. 200 hp at only 150lb. Thats insane considering the 084 weighs around 130 and puts out a conservative 40 hp. That is shocking though that the rig ended up weighing over 1000 pounds. Would have shot for around 750 at the most. But hey itll still move provided all your reduction drive parts can hold together at those high rpms. I see your spinning a sensenich prop. Very good choice there...well know and have been around forever and a day. Good luck on the build I look forward to the results. Word of caution though, go easy at first maybe just some idle om the trailer testing to make sure none of your bearings move of shift on you from all that thrust that prop is guna do.

best of luck and great looking boat.
Steve

[dr.peck76]

Here's a few more pictures of my progress. Haven't been around the forum for a while. I finished a tear down of my rigging and finalized the welding on all the tacked bits, added some black paint and began reassembly. I finished the UHMW install and ended up using this for sealant. Corky, I couldn't find that 5200 product from 3M locally, and after talking to a marine mechanic he suggested this.


I've almost finished the front deck with only a little cleanup to do and also have the floor installed. Also the fuel tank is finalized, painted and installed.


I did end up modifying an auto belt tensioner. I bought one from a scrap yard for $20 and then had an aluminium sleeve machined to increase the pulley width for my belt.

I'll remove it for a little cleaning but I wanted to get a pic for you guys. We had a decent discussion on another thread around this.
Anyway the weekend is here and with any luck I'll have the wire on the cage by the end of it and then.....trials

[Corky]

i'm glad you've found a sealant that worked for you........The idler looks great with the added advantage you can just order another from the auto parts store if it wears out....I was wondering how your build was coming along ...It's tough working on the fun stuff and still getting the chores done....

[dr.peck76]

I hear you there On finding spare time Corky. Thanks for the encouragement. I got the rigging and motor remounted in the hull this morning. Locking all the fasteners with either cotter pins, stainless tie wire or blue locktite. Very tedious but I certainly don't want some thing vibrating loose.

After I finish the mesh on that cage, I'll mount some brackets for lighting and reinstall the assembly. Then final wiring, a couple guards......The list isn't getting any shorter is it???lol

[dr.peck76]

So a couple of days ago I drug the airboat out of the shop with the intent of an actual test. WELL! It surprised the heck out of me as I hit about 2100 prop RPM and it push itself off the wet gravel in my driveway and on to the snow in my yard. My wife heard the racket and grabbed a phone to video the carnage to ensue.... Again I've never even sat in an airboat before building this one and had no idea how it would handle. In the snow it was down right scary as there was so little friction slowing me down, I have a fairly steep hill in the yard and after scooting down I spun it around and climbed right back up with out a problem and slid into the wood pile beside the fire pit! HA HA. No damage, after buzzing around for about 5 minutes in the snow, I pointed it back to the shop and headed across the concrete apron and right back into my work space. And then I took a breath. Wow

I've spent a few days going over little things I've noticed after the shakedown. I'm planning to head to the lake tomorrow where I can pay attention to things like RPM when it breaks free to max rpm on the trailer to verify the prop pitch is correct. I saw 7400 engine rpm which equals 2466 prop rpm but that wasn't constant.... and I only glanced down without really relaizing what I was doing as well.... time to pay attention. Wish me luck, at least the ice is still on and I shouldn't sink

[aerokirk]

Be careful on that ice! Especially since you've never driven an airboat ...(reference my crash video if you are curious). The boat will probably turn quickly with rudder input but that's not to say the boat will go in that direction, especially if you're moving at any rate of speed (remember - the bottom is FLAT). Sounds like you're definitely in the "FUN" phase of your build

[dr.peck76]

I made it back without major incident! Words of wisdom from you Kirk, I saw your video and that looked sketchy to say the least. Statistic report- breaks loose on dry ground(packed and loose gravel, wet and dry) at about 7400 rpm. Max engine rpm 8500. The sensenich salesman said it was a bit big for the power i'm making but i'm only about 170 rpm short of max prop so I think I will leave it as is. That's making 8 psi of boost. I can close the by-pass valve to the turbo cutting it back to 7800 engine RPM and 5 psi boost=2600 prop rpm. About a 4" draft.
After a few minutes buzzing around the broken ice at the ramp I had my confidance up and I drove up the ramp and my son climbed aboard. We cruised around the lake in the open water along the shore for about 40 minutes with out issue. It gets on step quickly and maintains plane at 4800-5200 rpm(1660 prop). We buzzed across the outlet(blocked by a bridge) and headed to the inlet where we could travel up stream to the first beaver dam. It was there I tagged the shore for the first time in the tight narrow stream in about 10 inches of water, with the rear of the boat in a turn I didn't initiate early enough, no damage though. We left the inlet and climbed back up on the heavier main ice and buzzed across the lake. This was a little scary as it didn't seem to want to hold a straight line until we were travelling faster than I was comfortable with. A change of direction seemed almost impossible at speed with the boat twisting but still maintaining coarse. Once along the opposite shore back in the reeds and open water where I felt better about control is where I peeled the leading edge of my side UHMW off on a log.

Finding the weak spots. I'll add a few more fasteners to that.