Yamaha 784cc into welded mod-v hull

86tuning
Posts: 52
Joined: 11 Oct 2017, 01:49
Location: BC Canada

Yamaha 784cc into welded mod-v hull

Post by 86tuning » 30 Sep 2018, 01:40

After hand tracing a squiggly orange line onto the laser line, I used a stick to clean up the curve.
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batten! for starboard bow cut edge
The black line on the right, on top of the squiggly orange line is what I'm cutting. The squiggly black line was when the laser wasn't centred properly :o
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cleaned up line to cut
I also slipped a piece of sign board in between, and traced the line onto that. So I have a template for the other side. And a permanent record in case I want to try this again. That's what the dirty white wedge next to the spare helmet is.
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other side, mirror image
Next, have to gather up my nerves and cut it all out using my cordless circular saw. Then notch the corner seam so I can flex the side panels to meet the bottoms, then mark out the filler panel where the chine curves up the bow. But I'm getting ahead of myself here. Gotta tidy up the space, and mark and cut out the transom piece.

See you on the water

Brian

RazorBaits
86tuning
Posts: 52
Joined: 11 Oct 2017, 01:49
Location: BC Canada

Yamaha 784cc into welded mod-v hull

Post by 86tuning » 21 Oct 2018, 20:40

I learned a bunch about cutting thin metal sheet. It needs to be secured and rigid, because when it flexes the saw jumps around and kickback is somewhat dangerous. I'm glad to have all my fingers still.

Replacing the 32T non-ferrous metals sawblade with a 60T oshlun non-ferrous sawblade helped a lot. Along with a small amount of lube, and properly securing the material so that it is as rigid as possible did the job. Felt like I was cutting plywood, other than the noise. Bonus, it smells like buttered popcorn when I'm cutting. Cooking spray is easily cleaned up before welding, and apparently traces of it won't contaminate welds as much as petroleum based lubes.
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material screwed to 2x6 board as a rigid backing plate. screws countersunk to allow saw to ride smoothly
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lubricant. gloves. hearing protection.
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off cut pieces are symmetrical!
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progress!
With the centre seam cut-out complete, I couldn't wait to bend up the nose to see what the boat will look like. It's temporarily held together with a strap so I can visualize it.
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checking alignment
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the nose seam, as seen from the front.
I'm pleased with the progress this weekend. Next I need to find a helper to roll the hull pieces so I can cut the side panel. Then roll over again, and mark the rest of the nose. I will likely need to tack some braces in place to maintain alignment while I lay out the rest of the nose, so I'll need to get some 2x2 angles or similar stuff. Then I can mark out the transom and firewall and cut those out as well. I'm very happy with how simple it is to cut the aluminum this time around. First try was scary with the kickback. The Oshlun blade is awesome, and affordable too.

See you on the water!

Brian
Last edited by 86tuning on 03 Nov 2018, 21:17, edited 1 time in total.

86tuning
Posts: 52
Joined: 11 Oct 2017, 01:49
Location: BC Canada

Yamaha 784cc into welded mod-v hull

Post by 86tuning » 28 Oct 2018, 18:27

Upon bending the sides of the nose inwards, I found that the upsweep meant that the bottom panels didn't rise enough for my liking. Originally, I had planned to level the nose and have a completely flat front deck, level with the sides. But after seeing the upsweep, decided to try keeping it. For now.
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first try
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inside view, preliminary cut
I decided to raise the bottom panels further up for more upsweep. I notched the centre seam panels further back another 1.5ft and had another look. Trimming both sides the same turned out to be an interesting layout nightmare because I no longer had the original square end as reference point. Would have been much easier to make the notch bigger the first time. But I think it turned out okay the second time.
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front view
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inside view of nose

Still have to make space to dismantle the waverunner, so I can measure the engine and jet drive layout, and build the jet inlet.

See you on the water.

CedarRiverScooter
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Joined: 13 Nov 2014, 08:01

Yamaha 784cc into welded mod-v hull

Post by CedarRiverScooter » 29 Oct 2018, 08:38

Is that a vintage Miata in the background?

Your boat is going to look great!

86tuning
Posts: 52
Joined: 11 Oct 2017, 01:49
Location: BC Canada

Yamaha 784cc into welded mod-v hull

Post by 86tuning » 30 Oct 2018, 01:42

CedarRiverScooter wrote:Is that a vintage Miata in the background?

Your boat is going to look great!
Hah thanks! It's a vintage ae86 corolla. Not mine, but very much like my old car. We take these old beaters to the track and have some fun. Some guys set them up for drifting, but that's not really my thing.

My old car was very stock looking, but far from stock.
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my old ae86

86tuning
Posts: 52
Joined: 11 Oct 2017, 01:49
Location: BC Canada

Yamaha 784cc into welded mod-v hull

Post by 86tuning » 03 Nov 2018, 20:55

A bit more progress today. I'm not ready to weld quite yet, need to finish layout and cutting first. So to keep the hull rigid for proper layout, I had to make a specialty clamp to hold the hull chine to my work cart/jig.
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specialty clamp
The other clamp I made is to hold the gunwales in alignment so I can flex the nose and bend it all up.
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fancy clamp number 2
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close up of clamp 2
Need more clamps! Just like horsepower, money, speed, the answer is always MORE!
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nose
The nose curve looks fair...
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fair curve
Once the nose was rigid, I could properly lay out and mark up the nose. I marked the inside of the starboard bow area with chalk. Note the faint green line. Much easier to undo temporary chalk markings vs sharpie marker.
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green chalk line
Next I used a stick to clean up the chalk line and mark my cut line with a sharpie. Well, a fiberglass sand flag pole.
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batten to mark cut line
And then screw the sheet metal down to a 2x6 for rigidity and to make a safe clean cut. Screw heads were countersunk, then buzzed with grinder to ensure no high spots to catch the saw base.
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countersunk screws
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cut with circular saw
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symmetry!
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bow profile
See you on the water,

Brian

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onthewater102
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Yamaha 784cc into welded mod-v hull

Post by onthewater102 » 06 Nov 2018, 14:47

Sharpie is a lot easier to work around. Erases from the surface of the aluminum with denatured alcohol on a rag.
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eshaw
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Yamaha 784cc into welded mod-v hull

Post by eshaw » 06 Nov 2018, 22:45

The bow rise reminds me of the style you see on a airboat.

86tuning
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Yamaha 784cc into welded mod-v hull

Post by 86tuning » 09 Nov 2018, 02:19

eshaw wrote:The bow rise reminds me of the style you see on a airboat.
Technically, I believe the hull style I'm building is called a Garvey. But I've added chine flats for some grip in turns, as I won't have a skeg hanging below the hull.

As for sharpie vs sidewalk chalk, I used both. The sketch line with chalk was easier to manage, just so I could see where things were going. Once the batten was clamped down to fair the curve, I marked the cut line with sharpie.

Honestly, I wish I knew what I'm actually doing. So many times I've felt that I'm in over my head. The tricky parts are yet to come.

See you on the water,

Brian

CedarRiverScooter
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Yamaha 784cc into welded mod-v hull

Post by CedarRiverScooter » 09 Nov 2018, 09:08

Before you clamp up the seams, scrub the heck out of them with a strong solvent to remove the sharpie ink.

I mistakenly used a whiteboard marker (only cause it was just laying around) & even thought I wiped it off / wire brushed, it made my welding very difficult.

86tuning
Posts: 52
Joined: 11 Oct 2017, 01:49
Location: BC Canada

Yamaha 784cc into welded mod-v hull

Post by 86tuning » 17 Nov 2018, 23:47

Thanks for the tips guys. I finally have some progress to share.

I found out my buddy had a welder in his garage. Wasn't his though, so I had to find our mutual friend, and talk to him about selling it.

"Sorry, it's not for sale."

"Well, can I borrow it?"

"Sure, use it as long as you like. If/when I need it, I'll let you know."

Wooohooo! Free welder! Not sure if he's ever getting it back though. So first thing I do when I get it home is to build a cart for it using an old engine stand and some random scrap, plus some swivel casters.
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the start of the cart
Then I added some MIG gun holsters on the side, for convenience, and the second one for 'storage' position. Yep. Built a cart for a welder that I don't own. Silly, but way better than lugging a welder around, and worrying about tipping a gas bottle. It's a Lincoln MigPak 180, a basic 220v welder that you can get at Home Depot or other big box stores. Doesn't have continuously variable voltage, but does have variable wire speed.
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The MigPak 180
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second holster for storage postion
I installed a new liner, tossed out the fluxcore wire and liner it came with, and installed an 035 contact tip to match the 030 wire. This 180 uses the same consumables as my SP125 so I didn't need to buy more stuff!

Then I started tacking up the hull.
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tacking the keel seam
And of course, have the magic eraser to deal with the mistakes
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magic eraser
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nose tacks
I marked up the transom using CAD. Not autoCAD but BoatCAD. Cardboard Aided Design.
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transom panel in CAD
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transom height
There's not a lot of freeboard in this design, but it's a full height transom. I
should just have enough side height to clear the engine. Might have to add a bit with some pipe on the gunwales.




Also started tacking up the nose, and making the filler panels. Then got carried away and started welding the nose seams.
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inside nose welds
Was happy and excited that I didn't have feed issues with the Lincoln MigPak 180 and a new liner. Voltage and wire speed settings are at maximum. Can't believe I tried so hard with the 110v unit before using the 220v one. Now I have a separate welder for steel and aluminum. Haven't pulled the pin to get a spool gun yet. I'm stubborn like that though. Some of the welds are covered with black soot. Welding aluminum is nasty stuff. Even with a filter mask.

Also quite pleased that I haven't had to use a lifeline and "call a friend" to come weld this thing so far.

See you on the water,

Brian

86tuning
Posts: 52
Joined: 11 Oct 2017, 01:49
Location: BC Canada

Yamaha 784cc into welded mod-v hull

Post by 86tuning » 03 Dec 2018, 01:12

Well these past couple weeks have been somewhat productive. I managed to take the hull off the cart/jig and put it outside in the rain on my trailer. I have it nose up so that it doesn't fill up with water and bend before I put the interior framework in place. I also managed to get the ski inside so I can take it apart. First order of business, remove the pump and check for wear and damage. Also confirm pump size at 155mm.
155.jpg
confirm 155mm pump
impeller.jpg
nicks but no scoring on wear ring
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teardown
I need to strip the impeller shaft so that I can have it shortened and re-splined. I did talk to a machinist that does this sort of thing, but he needs to see the bare shaft, to see if it can be modified with the tooling he has.

It turns out that you need two special tools to remove the impeller from the shaft. 1-1/16" wrench, and a spline tool to hold the shaft in a bench vise. To remove the shaft from the stator housing you also need a hydraulic press. The tool itself is available from various sources for US$11 and is only a few days away if I lived in the USA. But in Canada, there are not many local options. I was ready to order off eBay and wait for shipping, but lucky for me the local boat shop has the required Yamaha spline tools.

NOTE: the impeller is left-hand thread. So to take it off you have to pretend to tighten it! It's also quite tight, probably 100+ ft lbs torque. Properly secure the spline tool in the bench vise, slide in the shaft, and with the stator housing well supported, yank on the wrench. Being a little guy, I stood on the bench and stomped the wrench to crack it free, much to the amusement of the techs at the boat shop. I'm so lucky they let me do my own work. I spoze it's free entertainment for them.
impellershaft.jpg
impeller shaft
I still need to press the bearings and sleeve off the shaft, but it's at the point that it can be measured. And easily transported.

With the pump out and apart, I pulled the engine. Remove exhaust pipe (again) to access the throttle and choke cables. Remove fuel lines and oil supply line. Cap oil reservoir so I don't lose a gallon of oil into the bilge. Removed the carburetor to reduce chance of impact damage. Removed power valve control cables. Unplug ignition control box from instrument panel. Unbolt mounts and lift out engine.
crane.jpg
engine crane
Made a small cart to make it easy to tuck the engine into a corner. Re-installed carb, airbox, and exhaust manifold so I can measure the package. It's 22" tall. 22" wide. And a tick over 19" long not including the exhaust. Weight is about 120lbs but I don't have a scale to properly weigh it.
cart.jpg
engine on the rolling cart
Next weekend I plan to disassemble the rest of the ski and maybe take the upper cap off so I can properly measure the engine mounts and figure out how to make the pump inlet and engine mounting rails out of metal.

See you on the water,

Brian

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