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SC Designs
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Your craftsmanship looks great, but to me your spoon looks like it could be part of your problem. The spoon needs to look like the underside of a spoon that's in your drawer in the kitchen, all flowing and smooth. The angled edges of your spoon can disrupt the water flow and cause air to enter the pump. As far as the porpoising, I have learned that it is more of a weight distribution issue than a trim issue. I put the fuel tanks in the front of my builds under the front deck to help balance and equally distribute weight in the boat. The more weight in the rear means more bounce. Next time you take it out, put a buddy in the front of the boat and see if that stops the porpoising. Hopes this helps some.
So...gps'd 34 with three dudes upriver today. Ran it as shown in the last photo. SC, your right. Dude up front leveled the boat out, but also wetted out the boat A LOT. still cavitation to the point of not being able to hole shot this pile, but better than before with the pad. My buddy was able to weld up the loader grate today, so this weekend I'll give it another whirl.
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Been testing this thing with 30mph lawn chairs. Gonna make up some brackets for these today, figure out how to wire a ski doo tachometer to this here electrical box, and try to get a new dash bezel made to doll up the cheese ball helm. Further tests are on hold til CA DMV returns my paperwork. Been bootlegging this thing around for the last two weeks, and decided I don't need my hard work impounded. Registering home made boat is a hurry up and wait game, it seems.
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So...trailer got a new coat of paint, as I got tired of fiddling with aluminum scraps to make brackets for the seats. I ended up getting some cheap pedestals and knocking 4 inches out of them to arrive at what we determined was a comfortable seat height. Ended up being 9" from the floor to the top of the seat cushion...just like the lawn chairs. Go figure. Now I've worked myself out of this project til my buddy, that has been doing the welding, gets back from vacation. Side note; this whole thing started, cause he got a tig for cheap and wanted to learn. I started making parts and he started stitching, and here we are. Oh, and tach is in the helm, but yet to be wired; lots of head scratching still on that one.
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Still fumbling around with this tachometer. If anyone is willing to chime in on the wiring, it would be greatly appreciated. It's a 1994 ski doo 587 tach, and a same year sea doo gts everything else. Thanks in advance for any assistance.
...finally got some seat brackets mocked up and tacked in. Not much progress, otherwise. The aat helped, and the boat was noticeably faster with this addition, although I didn't think to bring the gps. Still suffering from cavitation, but I'm reluctant to tear it all down currently to re do a spoon. Also, scrapped the ski doo tach for a micro tach instead simply for ease of installation. Once I get it all figured out, I'll put up some start to current photos.
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Flat_Bottum
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Good looking build so far. I had the same issues with my boat (same size as yours) till I made a home brewed loader grate for it. Cavitation was CONSIDERABLY cut down and hook up was unreal. However, I did loose a couple MPH with the grate. Was at 44 before and then dropped down to 41. Looking forward to seeing the rest of the progress.
So, my variation of the loader grate did, well, zero. Working on round three of that now. Flat Bottom, thanks for the comment, duely noted. I am curious how far down you had to hang your grate to create such drag to lose 3mph. At this point ide take a top end loss just to hole shot this thing. When I built this, I used the factory sea doo shoe/ pump flange. Here's a photo of the tunnel that was welded to the outside of it. It was left with substantial gaps. Am I unreasonable to think that this design is keeping the pump from loading, or is it really just the lack of a spoon? Friday I took a day off just to sort some of these things out. One item is to take out as much center strake as reasonable. Thanks again for suggestions.
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Flat_Bottum
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I had it hanging about 2" below boat bottom. It grabbed all the weeds I can tell you that. From looking at your intake, I would say that you need to grind/sand those side pieces down so you have a seamless flow of water entering your pump. It looks like there is too much restriction going on. What are those fins on either side of your intake?
EDIT: I just seen you had mentioned that in your above post haha. Yes, I would agree with you fully that it needs to be cut out of there and polished up to make it nice and smooth.
EDIT: I just seen you had mentioned that in your above post haha. Yes, I would agree with you fully that it needs to be cut out of there and polished up to make it nice and smooth.
CedarRiverScooter
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Great all metal build!
My experience is that the pump intake needs to be a few inches down below the main surface of the hull to prevent sucking in air.
As you already realize, the non-smooth tunnel is also an issue.
You could use epoxy filler to fillet those corners.
I fixed porposing by changing the angle of the pump mount. That was not a 1 hour job, had to raise engine, etc.
Good luck, 40 mph in a flattie is a thrill.
My experience is that the pump intake needs to be a few inches down below the main surface of the hull to prevent sucking in air.
As you already realize, the non-smooth tunnel is also an issue.
You could use epoxy filler to fillet those corners.
I fixed porposing by changing the angle of the pump mount. That was not a 1 hour job, had to raise engine, etc.
Good luck, 40 mph in a flattie is a thrill.
Couple updates since the last post. I haven't had a chance to seal up the pump shoe, but got a new scoop on the grate, and it seems to have helped. Still going to build another one that's smoother and a little larger. Also, for balky got these seats in...white was a terrible choice...but I knew that already.
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Well, it’s been a while. Been prodding around here occasionally, and little done on the boat. Sealed the intake, I think I’m done fiddling around with intake grates and scoops. It hooks now, and ran 39 with two dudes the last time out. Next will be to strip it all down and shoot the inside with some spray lining...just have to bring myself to spend the money.
Here’s a gratuitous shot of the business end, as it’s gonna stay.
Here’s a gratuitous shot of the business end, as it’s gonna stay.
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Ok..Boats stripped down for final welding and paint. Added a hatch up front, and for jollies I’m going to weld a bung on the intake for a pressure gauge (guess I’m not done making grates for it). Also, I seem to keep knocking paint off of stuff and polishing. The exhaust was the most recent item. Lastly, for now; I acquired another pump. If anyone can school me on the possibility of this working, I would appreciate it tons. The part number from the impeller says it’s a 10/22 pitch. Will this jive with the 587 I’ve got in the Boat, or will it not have enough balls to spin it? Thanks, and happy holidays.
