IO 520 Build on 12 foot Hamant

Aircraft powered airboat discussion.
Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

IO 520 Build on 12 foot Hamant

Postby Hardtail » Sat May 18, 2019 10:48 pm

I found this older 12' Hamant hull with rigging that was in bad shape, I had already purchased an IO 360 Lycoming that was off an Airplane with prop strike for this Hamant. But then I found an IO 520 Continental for sale and bought it. Both engines I bought with out hearing them run first, just took a chance on them having just come off an airplane, I also got the Log books with them. I'll back up a little to let you know what brought me to this Build. Carb Ice. I have hunting property in Minnesota that only an airboat can cross, when it's warm out, like above freezing I have no problem with my O 360 on 10 foot Franny Tayler, But this year the temp dropped down to 17 degrees and I could go about 150 feet at a time then stop till the ice in the carb melted. So when I got back in Miami I started to build Carb Heat box off the Exhaust Manifold and a fresh air mixing box under my seat so I could adjust the amount of hot air with the fresh air to keep carb ice from happening. Then I started shopping on the internet for fuel injected aircraft motors, so now I got 2 of them, and I am hoping I'm on the right track
Attachments
IMG_2797.jpg
IMG_2796.jpg
IMG_2009.jpg
IMG_1933.jpg
IMG_1932.jpg
IMG_1867.jpg
56916894290__7DAD1616-667E-4408-B204-B1DDB599B5EC.JPG

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Sat May 18, 2019 11:15 pm

Started the Carb heat box
Attachments
IMG_1641.jpg
56427189890__8CD14152-E3E2-4D85-864C-09A89C98564B.JPG
IMG_5968.JPG

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Fri May 24, 2019 7:47 pm

Got the webbing paint on the inside and the outside stripped today,
Attachments
E5BD8004-AB9A-49D1-8410-40B9134E5541.jpeg
7A0CCF9B-1339-4088-A510-C5C8159EBC05.jpeg
83788028-33D5-42B6-97D5-4B56BE2FC97F.jpeg

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Fri May 24, 2019 8:01 pm

yesterday we welded on the walk boards

User avatar
lilly-Pad
Site Supporter - I
Site Supporter - I
Posts: 644
Joined: Sun Oct 05, 2014 11:21 am
Location: Homestead Fl

Re: IO 520 Build on 12 foot Hamant

Postby lilly-Pad » Fri May 24, 2019 8:52 pm

looking good Bruce , should not be too long before the maiden voyage
12 ft Don Davis / 0470 conv / 68 NGQ , A.A.O.F member

Best laid plans of mice and men, wont always get you laid.............

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Sat Jun 08, 2019 7:01 am

IMG_2970[1].jpg
Got the Motor and motor stand mounted

User avatar
lilly-Pad
Site Supporter - I
Site Supporter - I
Posts: 644
Joined: Sun Oct 05, 2014 11:21 am
Location: Homestead Fl

Re: IO 520 Build on 12 foot Hamant

Postby lilly-Pad » Sat Jun 08, 2019 12:41 pm

looks almost ready to ride
12 ft Don Davis / 0470 conv / 68 NGQ , A.A.O.F member

Best laid plans of mice and men, wont always get you laid.............

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Sun Jun 09, 2019 7:21 am

Hoping to have it ready for unity weekend July 13th in Okeechobee

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Wed Jun 12, 2019 9:58 pm

shouldn't be long now
Attachments
IMG_3029 (1).jpg
coming along

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Wed Jun 12, 2019 10:03 pm

Got the battery in and wired
Attachments
Image-1 (1).jpg

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Wed Jun 19, 2019 10:42 pm

IMG_3091.jpg

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Wed Jun 19, 2019 10:43 pm

IMG_3089.jpg

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Wed Jun 19, 2019 10:44 pm

IMG_3087.jpg

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Thu Jul 04, 2019 6:55 pm

My First Ride I had trouble steering, need to fix the ratio, the steering is way too hard, but the motor runs great.
Attachments
IMG_3165.jpg
IMG_3155.jpg

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Thu Jul 04, 2019 6:57 pm

I have a bad hop when I get over 25 MPH, any help on how to fix that would be appreciated

lariat
Southern Airboat Member
Posts: 338
Joined: Sun Mar 27, 2011 8:27 pm

Re: IO 520 Build on 12 foot Hamant

Postby lariat » Fri Jul 05, 2019 4:07 pm

I see you have a trim tab.....does the use of it take care of the hop?
Severval things could help.....
More forward weight
Different motor angle
Jacks in the hull
Is the bottom true??

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Sun Jul 07, 2019 6:01 am

Yes the trim tab helps till I get over 45 then the bow digs in and splashes water out ahead of me and I get wet.
Yes I have 2 jacks, one in the back 16" from the transom and the other is 4 feet from the transom.
I haven't checked the bottom, has poly on it, it looks good. I'll take some pics of it maybe there will be some clues
The motor is Level with the inside bottom of the boat,
I have 8 to 9" from the prop to front edge of rudders

User avatar
keys2pines
Southern Airboat Member
Posts: 95
Joined: Thu Jun 28, 2018 10:55 am

Re: IO 520 Build on 12 foot Hamant

Postby keys2pines » Sun Jul 07, 2019 8:25 am

Sounds like it has a hook in the bottom. Mine did the same thing until I put a jack in it. The jack helped a lot, but my bottom is still not straight. I still get hop, a little trim tab takes care of it, but it doesn't run on the nose anymore. I would definitely put a straight edge on the bottom and adjust the jacks.
12x6'8" Taylor deckover, 383 DD, 72" Sensenich JM

User avatar
Slidin Gator
Site Supporter - IV
Site Supporter - IV
Posts: 618
Joined: Sat Feb 03, 2018 11:33 pm
Location: Jupiter Farms, Florida

Re: IO 520 Build on 12 foot Hamant

Postby Slidin Gator » Sun Jul 07, 2019 1:30 pm

Hardtail,

No doubt you want to make sure the hull is true, but I assume that you looked into that during the build. Assuming hull is good, pitch the aft end of the engine down a bit and run it again.
I grew up thinking I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540, 72” NGQ. A Bob Stossel original.

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Sun Jul 07, 2019 6:50 pm

Hi Slidin Gator
The engine aft is as low as it can go, would need to cut the engine stand down to lower it.
Would Raising the aft end of the engine cause more nose dive or hop ?
My 35 gallon gas tank is below my seat, I could put it under the engine if I raise the rigging above the boat sides in order to slide it in place.
That way I would have more weight aft.
Would new poly do the trick ?
I noticed the poly has some waves in-between the rows of screws, so I'm thinking properly installed poly
would straighten things out

Sounds like it has a hook in the bottom. Mine did the same thing until I put a jack in it. The jack helped a lot, but my bottom is still not straight. I still get hop, a little trim tab takes care of it, but it doesn't run on the nose anymore. I would definitely put a straight edge on the bottom and adjust the jacks.

Keys2Pines

Today I tried to put the front jack up as much as it would go and still the same, Then I tried to push it down as far as it would go
and no change, still hops, I can ride as long as I use the trim tab, I have to slow down in the turns so I don't get so wet,
I don't know if I replaced the poly it would fix the problem or just throwing more money in an old boat.

User avatar
Slidin Gator
Site Supporter - IV
Site Supporter - IV
Posts: 618
Joined: Sat Feb 03, 2018 11:33 pm
Location: Jupiter Farms, Florida

Re: IO 520 Build on 12 foot Hamant

Postby Slidin Gator » Sun Jul 07, 2019 8:01 pm

Hardtail,

Engine/prop trim and weight adjustments on an Airboat are the same as a kicker boat. Point the prop up (engine aft higher) and you lift the nose with more potential for hop. Point the prop down (engine aft down) and you push the nose down. Weight is the same, you would want to move weight forward to hold the nose down, not aft. As it is, the fuel tank under your seat is a good place, you don't want the fuel tank too far forward or the boat handling will change drastically from full to empty.

Waves in the poly is certainly no good, but rectifying that is backing up a whole bunch from where you are. I am sure you saw the waves when the hull was sitting in the Florida sun. UHMW changes dimensions significantly due to temperature. Does the poly straighten out at night or does it still have waves in it? You may even want to live with loose poly down here so it has slack for when you go run the boat up North in the winter. Normally poly needs to be installed in full sun so it is a shrink fit to the hull. When it cools down the poly is essentially stretched like a drum across the hull. But take it too cold (vs. install temp) and the poly might buckle the hull??

Given where you are at on the build, and your plans to run it up North in the winter, I would try all the other potential fixes first before dismantling the boat for a new poly job. You say you get wet when you turn, is this because the trim tab is down?

You should not need to take a torch to the engine stand to adjust the prop pitch. How is your engine stand mounted to the runners? If the stand has flat feet, just add some washers under the front legs where they mount to the runners. That will pitch the prop down a bit, which pushes the nose down. As you get up to higher speed, the grass rake lifts the nose so you need more force down on the nose to compensate. See what you can do to pitch the prop down and eliminate the hop at 25 mph, then we figure out what she needs at higher speed.

You did not mention trying any adjustment on the rear jack?
I grew up thinking I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540, 72” NGQ. A Bob Stossel original.

Hardtail
Site Supporter - I
Site Supporter - I
Posts: 247
Joined: Sat May 02, 2015 9:35 am

Re: IO 520 Build on 12 foot Hamant

Postby Hardtail » Wed Jul 10, 2019 5:52 pm

Slidin Gator
The rear jack, I don't know what to change with it, looks like I can only push down with it unless I attach it to the runners and be able to lift up with it,

the engine stand is welded to the angle iron that is attached to the runners of the boat, no adjustments there.
If I need to flip the boat, the cage is 1 piece and the engine stand along with the seats and gauges is all another piece.
so to flip the hull over to replace he poly wouldn't be that big of a deal, so I might just need to do that.
The poly is attached with Phillip head screws, looks like it has been replaced once before cause I can see where the old holes have been filled in.


Return to “Aircraft Power Only”

Who is online

Users browsing this forum: rowdy1 and 11 guests