outboard swap and trailer bunk redo

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handyandy
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outboard swap and trailer bunk redo

Postby handyandy » Mar Thu 23, 2017 1:21 pm

For anyone interested some work I recently did on my boat and trailer. Posted this in a boat forum I'm on as well but thought maybe some on here might find it useful or like to see it.

So my boat was short shaft 16" transom, and it started with a 40 prop tiller I ran for few years. Then added a jack plate which helped with shallow water capabilities, but I really wanted a jet. Then almost two years ago I swapped to a 1993 60hp tiller short shaft prop mercury with intentions of making it jet. I hunted down a jet lower for it that I got second hand for a good price. Swapped out the long shaft drive shaft of the jet lower I got for a short one mounted it up on the engine and have been running it with the mecury made 60/40 jet for a while now. It wasn't bad it's a good running engine pushed the boat well hasn't really given me any troubles.

But when I first swapped the mercury I wanted a omc three cylinder. But at the time when I first wanted to swap to a jet I couldn't find any omc 56ci triples with a tiller. Or any non tillers cheap to convert to tiller. I came across the merc for a pretty good price and got the jet drive for it pretty cheap. But back around thanksgiving I found a ok deal on a really clean 1994 omc 70hp tiller with a jet already. I ended up buying it and left the mercury on through the waterfowl season as I didn't want the boat decommissioned for the swap during waterfowl season. So I started the swap about three weeks ago. It was a little more involved than just unbolting and swapping engines as the evinrude is a long shaft, so I had to weld up a extension for my transom. My trailer bunks had also seen better days so I figured I'd redo those as well while I was at it when I had the engine off.
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Re: outboard swap and trailer bunk redo

Postby handyandy » Mar Thu 23, 2017 1:23 pm

To start with I unbolted the mercury and lifted it off the back using a shop crane didn't photograph this as it's pretty straight forward unhook battery cables, unhook fuel line, loosen bolts support engine using engine hoist and lifting straps. With the help of a friend unbolt it and remove it carefully. Then I unbolted my jack plate. With the engine off I jacked the boat up slightly off the trailer on one end using a car jack with a block wood between it and the boat. Once the end of the boat was off the trailer bunks I slid pieces of 2x4 wood scraps between the bunks and hull to leave a gap between the bunks and hull. I then did the same on other end of the boat. I then slid long heavy duty tow straps between the hull and trailer. I have two post car lift in my garage so I backed the trailer in and positioned the lifting arms appropriately and hooked the straps to them to lift the hull off the trailer. Sorry I didn't think to take pics of the wood between the hull and trailer bunks and putting the lifting straps in.
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Re: outboard swap and trailer bunk redo

Postby handyandy » Mar Thu 23, 2017 1:24 pm

After getting it off the trailer I started removing the old bunks which were pretty warped and bowed and crappy. Part of my problem was the trailer only had cross members at the front in back to support the bunks no middle cross member to keep them from sagging and bowing in the middle. So middle crossmemember was one I made up using some old square tubing I had lying around. I measured it up welded it together fit it on the trailer then welded it on the trailer.

The welders I have are a lincoln square wave tig 175 that I bought used a while back 5-6 years which has been really good to me. I taught myself tig weld using it back in college, for home shop/hobbiest it's a great machine I've had zero issues with it. The MIG welder I have which I just bought a few months ago is a Hobart 190 that came with a spool gun. I can't say enough good about it. It's no industrial commercial shop welder but for the money you can't beat it I highly recommend it. I looked at every kind of mig and looked for used deals before pulling the trigger on it. It mig welds steel great thin and thick, and the spool gun works great. I was somewhat hesitant about getting it over the miller equivalent as the miller is lighter being inverter powered and has infinite variable adjustment for the voltage where as the hobart is transformer powered making it heavier and has 9 fixed variable voltage settings. The hobart is much cheaper though I bought mine through northern tool using a coupon for 700 something and it came with the spool gun. The Miller 210 which is about the equivalent is over a 1000 not including a spool gun. I didn't consider the lincoln welders in these smaller home shop migs as they are made in mexico and cost about the same. I wasn't going to pay about the same money for foreign labor that just me though lincoln makes good products I have nothing against them obviously since my tig is a lincoln machine.

Enough about welders here are some pics of the trailer after getting the bunks off and welded in the new middle crossmember. Sorry I didn't take a ton a photos I'm no photo journalist just thought I'd make this post anyways in hopes it might help others.
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Re: outboard swap and trailer bunk redo

Postby handyandy » Mar Thu 23, 2017 1:26 pm

pics of the bunks coming together
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Re: outboard swap and trailer bunk redo

Postby handyandy » Mar Thu 23, 2017 1:30 pm

After I got the new cross member in I proceeded to cut pieces of some old plate steel I had, and welded them on for trailer bunk mounting tabs. I spaced them evenly across each trailer cross member where I wanted to the bunks at. My trailer initially had two bunks I made it into a four bunk trailer. So I had to move my outer mounting tabs out a few inches, and added some more towards the center for two more additional bunks closer to the middle of the trailer. Four is over kill considering my boat is a 1554, but I figured spreading the weight of hull out over more surface area while being trailered and going down bumpy roads wouldn't hurt anything. Rather it be overbuilt than under built. The aluminum bar in the pictures on top was what I used to lay across the bunks to make sure there were all mounted level with each other.
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Re: outboard swap and trailer bunk redo

Postby handyandy » Mar Thu 23, 2017 1:38 pm

For the new bunks I used pressure treated 2x4's that were twelve feet long cut down to the length of the original bunks which were around 11ft long. I used stainless bolts to affix them to the mounting plates I welded on the trailer. Once I had the bunks bolted down a leveled out well I screwed pieces of the trek decking on top of them that the boat will sit on. This stuff is pretty slick allowing the boat to unload easily, a friend of mine with a mud boat did his bunks with it. I liked it enough I decided to use it as well. The benefits are it won't rot, and it won't hold moisture like carpet does so the wooden bunks should last longer. The wood is pressure treated now so it should last much longer than the previous bunks. Pressure treated lumber normally causes corrosion issues when in contact with aluminum, but the boat will be contact with the trek so it shouldn't be an issue. I bought three 8ft pieces of the 4" wide gray trek it was the cheapest that's why I used it. I ripped each piece in half down the middle long ways to make thinner strips that covered the tops of the 2x4 wooden bunks perfectly. I used a table saw to rip them down, it cut about the same as wood does just had to go a little slower while making the cuts due to the trek being denser than wood. I screwed down the trek pieces using stainless deck screws. I counter sunk all the screws into the trek so they wouldn't scratch the bottom of the hull.
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Re: outboard swap and trailer bunk redo

Postby handyandy » Mar Thu 23, 2017 1:43 pm

After getting the bunks done I set the boat back on the trailer and got started on the transom extension work. My boat is a excel that was painted with what is like a thinner version of line x or rhino lining. It was sprayed in and has held up great but was a pain in the arse to get stripped off where I was going to weld. I started by using my tig welder to weld up and fill in all the old holes from previous engines that have been on this hull. There were bolt holes still from the mud motor this hull originally came with then holes from having an outboard on it after that. I bought it used and it had a 40hp prop tiller outboard on it when I got it. I used a heavy duty wire wheel cup on my grinder to remove the paint/coating on the boat from around the holes then a sand flapper wheel to clean up the aluminum a little further then a stainless wire brush. When welding aluminum getting it clean is imperative to getting good welds. Steel is much more forgiving in terms of welding if contaminates are present. Once the holes were cleaned up I started welding them shut. Then ground them smooth after welding.
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Re: outboard swap and trailer bunk redo

Postby handyandy » Mar Thu 23, 2017 1:44 pm

after welding the holes up
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Re: outboard swap and trailer bunk redo

Postby handyandy » Mar Thu 23, 2017 1:47 pm

After the holes were all welded shut I had to strip off and clean up the top of transom to be able to weld a extension on it. I used a piece of 3/16" wall 2" x 4" rectangular tubing for my extension. I had to make small angle cuts on the bottom of the rectangular tubing to fit the transom just right. I used a band saw to make those cuts to get it to fit well. Once it fit well I cleaned up the top of the transom and the extension with a SS wire brush to prep it to weld the extension piece on to the transom using the spool gun on my mig welder. I started by tacking the extension on at each corner and in the middle on the inside of the boat and the back. to weld it fully I made passes welding about 3" at a time to avoid getting to much heat in one area and warping it. After making a pass on one spot I'd move to the other end of the opposite side of the extension to make another pass then would let it cool and while I took a beer brake.
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Re: outboard swap and trailer bunk redo

Postby handyandy » Mar Thu 23, 2017 1:50 pm

sorry meant to have these pics before the others
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