Took her out for another spin

[interalian]

Crisp fall day and a flat lake, so I took the tinny out for another blast. Timing is now fully advanced to spec. Just need a proper prop, as it's revving a tad high. But maybe just a cupped 17" SST if I can find one.

https://youtu.be/sbLxgYs2kbM

 

[Fed]

Lop sided weightwise, T&T or transom movement and that flapping vinyl cover would drive me nuts.

I'm guessing you're pretty happy with the motor now, it sounds & runs great.
What prop is on it now & what's it's current WOT RPM?

FWIW I can level my boat on the run by trimming it, for you it would be trimming it out but all boats are different & what works for me may not work for you.
I've got a bit of an OCD going on about things being straight, it's like a curse.

A very good result for your efforts, what's next?

 

[interalian]

The boat is very sensitive to weight distribution. When it's just me in the pilot chair, my 220 pounds of awesome (lol) tilts it to starboard. If I have another person in the passenger chair it rides level. Not a lot I can do about it except moving the battery to the port side of the stern. Fuel is two OMC cans, one at center and the other at port. Today the port fuel can was empty, center about half and battery and a full 2 gallon jerry at starboard. I'd thought a long time back that maybe a bow tank would help - plenty of room for one up there - or maybe a 12-15 gallon flat tank for back there would make more sense. Maybe some passive trim tabs would help too.

There's no looseness in the transom, but I do notice if I go from WOT to idle really fast, the motor pulls up a little as it drags the prop. Maybe the main ram is a little less than perfect - the top seal weeps a bit if I leave weight on it for a few days. Nothing serious, and the only movement in the rest of the clip is trimming up and down.

I'm very happy overall as she's running so smooth and strong. Not 100% confident in the tach accuracy, but it sounds like it's hitting 6000 at WOT to my ears. Looking for a decent digital tach/hour meter but they only have short cables so it'll have to go in the stern. Maybe in the spring.

Running a 13-1/4 x 17 aluminum prop. Still haven't found a 19 to try, but from what I've read a 17 SST is more like a 19 aluminum??

Next? Well, the lake gets drained mid-October so I need to get it home before then. I'm planning to take the motor off and strip all the parts that were never painted when it was originally built, and give it a complete paint job starting under the cowl, then doing the whole exterior. I'm keeping it the silver the 90 was rather than two tone with the blue the 140 came with. Guess I'm trying to complete the 'stealth' part of the project.

The boat needs a bit of work too, so I'll pull the seats and side panels, then re-wire all the 12V stuff. The original wiring is getting tatty and I think a fuse panel will be fitted next to the battery.

 

[Fed]

Yeah I just remembered the tilt ram won't hold against a lot of pressure, even giving it too much throttle in reverse is enough to allow the motor to lift so there's probably nothing wrong with it.

I'd be shooting to have the boat half a person (40Kgs?) heavy on the Port side so when you're alone it only swings half a person Starboard and with a passenger back to half a person to the Port. Then try tweaking with your trim.

Be interested in the numbers when you get a tacho.

I'm going to get one of those fuse panels too, right now all my wires +&- join in 2 single connectors under the dash with a single fuse at the battery.
Safe enough with no break of wire gauge but messy.
Just another thing to do on the endless list.

 

[interalian]

Good ideas for weight. When the boat was new, we hung a 7.5hp 'rude on the drop bracket port side, so it probably ran level with just the pilot that way. Battery and a 2.5 gallon can for the kicker on starboard, center 6 and port 6 tanks. Stern heavy when everything was filled.

I put a new bilge pump in this year and it didn't work. Chased the problem back to a ScotchLock I used for negative back when I installed it in about 1985 and the darned thing had failed. There are others in the wiring and they all have to go. Never really trusted them, and if you can only get 30 years out, especially so.

 

[Pusher]

You might want a bigger box when you order so you have spares, assuming you hook your running lights, cabin lights, bilge pump, cigarette lighter, tach, etc. up. That thing looks snappy!

 

[interalian]

I just have one 20A fuse in the thing now, and I was thinking:

1: 10A - Bow light/anchor light(no cabin lights)
2: 10A - Bilge pump and horn
3: 10A - 12V accessory plug/lighter
4: 2A - Instruments
5: 2A - Fish finder (Humminbird)
6: spare, or a second 12V accessory plug at the stern for a cooler

Can't think I'd ever put any other loads in, except maybe a stereo. But with BlueTooth speakers, I can't see doing that either.

And yes, snappy as all scoot. Not surprising with an extra few ponies.

 

[Pusher]

I just have one 20A fuse in the thing now, and I was thinking:

1: 10A - Bow light/anchor light(no cabin lights)
2: 10A - Bilge pump and horn
3: 10A - 12V accessory plug/lighter
4: 2A - Instruments
5: 2A - Fish finder (Humminbird)
6: spare, or a second 12V accessory plug at the stern for a cooler

Can't think I'd ever put any other loads in, except maybe a stereo. But with BlueTooth speakers, I can't see doing that either.

And yes, snappy as all scoot. Not surprising with an extra few ponies.

Might be the pendleton speaking but what is a cooler accessory plug used for?

 

[interalian]

Might be the pendleton speaking but what is a cooler accessory plug used for?

Without knowing the vernacular of a "pendleton", I'll take a guess: I've got a nice little Peltier cooler that runs on 12V. Keeps a sixpack and 4 sandwiches cool and takes about the max output of the alternator to run.

 

[Pusher]

Best whiskey I've had. Made in Pendleton Oregon "Let 'er Buck". They just finished up their rodeo I think (not that that matters).

Is that a home built deal? When I googled it, I came up with a bunch of electric cooling pad doo-dads.

 

[WernerF]

The highest rpm your video shows is 5500/5600 rpm at 1:14. The rpm at 3.22 and 6:58 is even lower. If that was wot then no higher pitch propeller.

 

[interalian]

Good ear - wish mine was so well calibrated! During the video, I never actually had it WOT - kept it back a bit as I'm not comfortable with the accuracy of the old '83 tach. I think at 1:14 I had it fairly close to max though. I was experimenting with trim as you can see too. Next time I'm on the lake I'll let it go WOT for some time and post back for another estimate.

Now, bearing in mind I'm running at fairly high elevation (Chestermere Lake is 3373') on fresh water, it'll run right off the tach at sea level should I take it there (no plans as our miled-up 3.0 X5 tow truck might not be up to the Coquihalla Highway grind up to 4100'. Summer trips do take us into central British Columbia on Kootenay Lake (1750') and Shushwap Lake (1140'), and I expect it'll run higher on those lakes at their lower altitudes.

Back when the boat was newer, it would do maybe 5200 indicated on salt at sea level and an indicated 41mph with a much lighter me piloting (160 lb vs 220...). On local lakes around 3400' elevation, it wouldn't crack 5000 and maybe 37-38mph. I'm getting 44 on gps with the extra ponies, at RPM similar to those in the video.

 

[jakedaawg]

Around the 5:50 marknit seems like you are porpoising. You mention it a little later. Were you running over old wake or was it flat?

If it was flat you might try a pencil lip at the stern. Just a little build up at the very back of the hull at the transom. Doesnt take much to solve it. I've only done it on wood or glass boats but there has to be a way to put one on a metal boat.

 

[interalian]

Yeah, it porpoises a lot. Lake was quite flat with just small ripples, no wakes. I can stop it if I bury the nose by trimming down. This hull is a pretty shallow curved V with fore/aft ribs about half way up each side of the V. You can see how shallow and the curve here:



The ribs are just inboard of the trailer rollers. Center profile of the hull is a shallow curve with the center rib ending flat a few inches forward of the transom. No pad.

I'm having trouble visualizing the pencil lip you're describing. Earlier this year I was looking at some passive trim tabs as a possible solution. Never liked the look of those whale fins that mount on the cav plate, so that's a no. I mounted the motor one hole higher than it was originally mounted as the cav plate was a bit below the bottom of the hull, and always ran buried previously.

 

[Pusher]

I can't picture how a lowered stern would keep a front heavy bow from porpoising. How does the physics work?

 

[jakedaawg]

I can't picture how a lowered stern would keep a front heavy bow from porpoising. How does the physics work?

It doesnt porpoise do to bow loading.

Typically I have found that boats that are stored on roller trailers and sometimes lightweight metal boats develop a bow to the hull. Then when trimed you get the bow bouncing or porpoising.

Just a little lip at the stern, doesnt take much usually, gives enough bow down, or stern lift if you will, to aleviate the issue. Not so much that you cant trim, but enough to stabilize.

 

[jakedaawg]

Many high performance boats incorporate this in the design. Allison for sure, and I believe Siebold as well.these are 100mph + boats, so it not quite the same, but it can work on others.

Some of the old woodys develop a bow and the easy solution is to place a strip of wood across the bottom of the stern.

 

[Pusher]

Huh, that makes sense now I think JD. Thanks for the explanation!

 

[interalian]

I'll take a look and see if there's any bow in the bottom when I get it back out of the water. Thought it looked straight when I checked it in the spring. But it does sit on a roller trailer, so...

 

[interalian]

Pulled it out of the lake today (2C nasty start - see other thread). Had it up to an indicated 48mph on the run across the lake.

Here's what the hull just in front of the motor looks like. There's a center rib that ends about 2 feet from the transom. Paint has never stuck well and I'd considered grinding it all off and re-doing, but that seems like an awful lot of work. There's a bit of white silicone remnant of an old transducer that's long gone.



Here's a straight shot along the cav plate with the motor mounted up one hole. With the motor sitting at its lowest mounting hole, the cav plate is below the hull and was always buried at plane, sending up lots of spray. One hole up and I can break the prop out of the water if I trim it too high.