Author Topic: Greetings from Finland  (Read 2298 times)

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Offline Tapani

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Re: Greetings from Finland
« Reply #20 on: June 28, 2022, 11:47:09 AM »
Hello again,

The more I run the boat the better it feels 👍.

Any idea of the peak torque rpm level of my motor?

I tried a few holeshot runs and from stand still and the revs raise to app 4500 at wot and stay there until more speed is picked up.

The acceleration feature in the Vesselview shows a rather constant 5.8-5.9 sec to 30 MPH. Feels good and quick enough, ambient temp 31C, water 21C.

I don't mind hitting the rev limiter at full power, no need to go that fast, really.

Kind regards from Finland,

Tapani

Offline Hyperacme

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Re: Greetings from Finland
« Reply #21 on: June 28, 2022, 06:01:00 PM »
2008 Mercury 80 HP EFI spec's

Offline Tapani

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Re: Greetings from Finland
« Reply #22 on: July 13, 2022, 01:54:47 PM »
Hello again,

Still trying to figure out and learn what affects what....

The distance from the transom/keel edge to the vertical plane at the center of prop blade roots is 56cm @ 0 trim (antiventilatio plate aligned with keel line).

Is this a lot? Compared to the 2 strokes of the early -70's?

The antiventilation plate is now 3/4" above the keel line, but is still under water at planing speeds.

Tapani

Offline Hyperacme

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Re: Greetings from Finland
« Reply #23 on: July 13, 2022, 03:15:08 PM »
All motors (20 inch shaft or long shaft)  from 70's until now are the same as far as shaft length, only difference is where it's mounted on transom.
I'm not sure how much your boat weighs but 40 MPH / 35 knots sound pretty good.
You could try a jack plate to fine tune .. but would cost a lot for small MPH/knots increase.
If you start to lift it a lot, you should get a PSI gauge so you know your getting good water pressure to motor at full speed.
It's hard to say what's your best set up .. Just keep testing until your happy ...
 

Offline Plugcheck

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Re: Greetings from Finland
« Reply #24 on: July 13, 2022, 07:43:25 PM »
I'd just like to add that folks spend considerable time, money, and effort finding what works best for their application.    As Gregg mentioned, as long as you have good water pressure, you can go higher.   It all depends on what you wish to accomplish, some it's longevity, some it's top speed, others it's yank multiple skiers up.   Enjoy the hobby, report your findings, and always pictures are welcome.
Michael
1979 CVZ-18 388 CI Vortec Mouse
1980 CVX-16SS 140 Mercruiser
1979 CVX-16 Johnson 175
2002 Bennington 2275CC 90 Mercury
1985 Intimidator project
1989 Lowe 200 Redneck fishin Toon
2001 Godfrey Sweetwater pontoon 115 Rude

Offline Tapani

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Re: Greetings from Finland
« Reply #25 on: July 13, 2022, 09:42:48 PM »
Thanks guys for your replies.

I have a pressure gauge for the cooling and it shows good numbers, over 20 psi at full speed, no fluctuation.

The distance I meant is in the prop shaft axial direction. To the rear from the transom, how far aft is the prop from the transom. If I understood correctly the water level rises an inch for every 8-10 inch.

My aim is to be able to trim to "0" at cruising speeds, 21-27 knots, without porpoising. This is not yet quite possible even with just me onboard.

I am trying to think about everything before installibg trim plates.

When the lake calms I'll take a few photos of the av plate at different speeds.

Tapani

Offline Hyperacme

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Re: Greetings from Finland
« Reply #26 on: July 13, 2022, 11:01:25 PM »
Not sure how "Setback" would affect your boat.
I think your right about the farther back you go the deeper the drive would be, But don't know for sure ..
I think setback would work with a very light boat with high HP.

Offline Hyperacme

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Re: Greetings from Finland
« Reply #27 on: July 13, 2022, 11:12:44 PM »
Doug has a light boat ( C500 about 700 lbs / 317 kg. ) with a 200 HP Johnson and 12 inches / 300 mm of setback.
He say's he's having  proposing problem and is going to remove 6 inches /  150 mm of setback.

Offline Tapani

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Re: Greetings from Finland
« Reply #28 on: July 13, 2022, 11:37:02 PM »
Hi,

Thanks for your reply.

I am not able to paste a linkhwre, but search for "Boost Speed with Outboard Engine Height Adjustments". And check "other variables".

I got the impression that motors have hugely different dimensions. And the lower end of the period 2 strokes look small compared to my motor.

My boat shell alone is roughly 500kg.

Kind regards,

Tapani

-edit: No, I am not looking to install "a set back", but thinking if I should still lift the motor further up .
« Last Edit: July 13, 2022, 11:44:07 PM by Tapani »

Offline Hyperacme

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Re: Greetings from Finland
« Reply #29 on: July 14, 2022, 11:07:15 AM »
Your boat/motor, gas, battery, etc. without you in the boat, comes to about 1600 lbs. / 725 kg.
I had a V156 with a 60 HP Johnson, gas, battery, etc. without me in the boat it came to about 1000 lbs. /  450 kg.
I was getting about 40 MPH/GPS / 64 kh.
On another boat if I added a 200 lbs. / 90 kg. passenger, I would lose up to 3 MPH / 5 kh.

You could be right about newer motor size, as the newest motor I owned was from the late 1980's.
I know Merc makes motor that are "High thrust" for pontoon's and heavy slow boats, maybe with larger lower units and lower gearing to swing larger props.

Are you still having  proposing problem ?

Offline Tapani

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Re: Greetings from Finland
« Reply #30 on: July 14, 2022, 12:13:13 PM »
Well, yes and no

I can always stay away from porpoising by trimming down. Having said that, it's clear that the motor would like to be trimmed higher under almost all conditions - except full 35 knots. It always gains rpm by trimming slightly up, and starts porpoising.

My main goal is to reach neutral "0" trim at cruise speeds.

If trimmed to "0" it will not ventilate if I open the throttle fully from stand still. But will porpoise soon after I reach planing speeds.

It's quite windy with big waves still, I will take a few photos of the av plate when the lake calms down

Tapani

-edit: I thunk the total weight is a bit more with all the gear I carry, tools, anchor etc. With four large adults the porpoising is much worse and less trim can be tolerated. But that's where the torque and the 4-bladed prop shine. Hole shot is still good  and 30+ knots easily reached (hits the limiter alone). I do not need any more speed
« Last Edit: July 14, 2022, 12:19:19 PM by Tapani »

Offline Tapani

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Re: Greetings from Finland
« Reply #31 on: July 15, 2022, 12:18:35 PM »
Hello again,

I went for a spin - 200m from home got stopped by the police, they checked my life vest, fire extinguisher and I had to blow in the alcometwr thing 🤗🍻. First time we've ever seen them here. Friday evening, some jetskis buzzing around so I guess it's good 👍.

I dis aeound 30 knots and took a few photos of av plate. I guess it's very close to the watwr surface, but still under it.

What do you guys think?

Tapani

Offline Tapani

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Re: Greetings from Finland
« Reply #32 on: July 15, 2022, 12:26:37 PM »
Bad choice of photos, the first one.

T

Offline Hyperacme

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Re: Greetings from Finland
« Reply #33 on: July 15, 2022, 01:50:31 PM »
BWI's (boating while intoxicated) have been in effect in Minnesota for over fifteen years now, not sure if everyone gets a breathalyzer/test or just persons who seem intoxicated ..
Set up is a compromise .. all depends on what you want. 

Offline thewillets

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Re: Greetings from Finland
« Reply #34 on: August 04, 2022, 10:40:55 PM »
That is great to hear, you have breathed new life int your classic.
1965 Futura 500 V164

Offline Tapani

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Re: Greetings from Finland
« Reply #35 on: August 12, 2022, 11:49:36 PM »
Thanks for your comments.

As explained, I raised the motor one more hole up. It sits now a full 3" higher than when I bought it. AV-plate 1,5" above keel line.

A huge improvement 👍

Check out hole shot recorded with my new GoPro 🙈.

https://youtu.be/dlW1JTXZBG8

It's actually 0-35 knots, you can just hear the motor run against the limiter.

I can induce porpoising at cruise speeds by trimming the motor up.

https://youtu.be/3KfsJME6IZY

But it runs real sweet at full song, just keeping the revs at 6000 and thus below limiter. I have a cooling water pressure gauge - steady 25 psi at full speed.

https://youtu.be/xdY8XMSIK-U

I need a lot more seat time before I can tell you more.

Kind regards,

Tapani