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Posts: 532
| I recently repowered my boat with a 40hp mariner, while i am still tweeking the set up in, I am wondering about what other people have for performance numbers like
(let it be known I am fully aware that different motor on different hull, different prop...all will yield different results. I am looking for a persons pesonal experence so I can compair it to mine)
Top Speed
Prop pitch
WOT
Motor heigth
kind of boat
brand of motor
gear ratio
I am asking these question to get a better idea of what a 40 should be capable of, before I lay out my numbers. Thanks |
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Posts: 3511
Location: Elk River, Minnesota | hiya,
I had a 1999 Johnson 50 hp 2 stroke 2 cyl on an alumacraft Lunker v16 Mag LTD console boat. This would be close to your mariner as 10hp is not going to be too much of a difference in performance.
top speed: 33 at 5500rpm (max rpm for range on motor)
prop: 11-3/4 x 17 solas alcup 3
gear ratio 2.42:1 (this was a powerhouse for gear ratio)
boat weight 660 lbs
Motor height: two bolt holes up off transom
I'm guessing you should see close to the same speed depending on your boat. Most likely you will have a lower pitched prop due to a gear ratio of either 2:1 or 1.85:1, putting you at a 15 pitch or maybe even a 13 with the 1.85:1
Steve |
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Posts: 532
| I am running a 14 pitch 4blade solas amita 4. What has me puzzled is my WOT is 4400rpm, no where near the 5000-5500 range.
I have 27mph on the gps, that translate to 9% slip. It is a 2:1 gear case. The motor isnt all that much faster (if at all) to plane than when i had my 25 on the back of it, but i did get 5-6mph top speed faster.
Compression is 135psi both cylinders. I am just wondering if she is starving for fuel, or maybe ignition timing is a little off. I may have to do a link and sync.
It just seems odd, it is on a 14.5 foot aluminum boat 65 inch bean side console, loaded down with two men it might weigh 1000-1200lbs. I think it should be doing more. I still have some tinkering to do. |
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Posts: 3511
Location: Elk River, Minnesota | Hi again,
I would say that much of that might be due to the extra blade on the prop, and you are loaded with people and gear.
If you can, take the boat out on a day that has a light wind (enough to make ripples but not waves that will bounce you), with just you and a light load of gear. Get her out and open, trim it up and see where you are at.
My gut says you will get to about 4800 with that prop which usually would mean you are over pitched, but....if you get a good 3 blade like the amita 3, your rpms will be higher and you will see more speed and probably not even notice any difference in handling. A boat of that size should not need a 4 blade prop. By the way, what brand and model of boat? Sounds a lot like a lund rebel 1440 or a lunker 145 from alumacraft...
Steve |
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Posts: 532
| It is a monark 1400sc, semi vee 3-6degree deadrise not really sure but it is not flat.
It just isnt sitting right with me the WOT is so low, even with the forth blade. I was in the same ball park with you on it should be at least upper 4000s or low 5000. It did not come with a prop so I made a guess thinking a 14 pitch four blade would be in the sweet spot for a smaller boat like mine.
My mariner 25hp with a four blade 11pitch amita 4 did 21-22mph and spun 5600rpm with 2.25:1 gear box with the same load (minus the weight difference between the 25hp and the 40hp). I went to 4 blade on the the 25hp motor because it vented very badly in corners and the forth blade fixed 80% of theventing issue. So since then I have been a big fan of 4 blade props |
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Posts: 3511
Location: Elk River, Minnesota | The 14 pitch in a 4 blade would be a little harder to turn than a 3 blade 15, so that makes some sense to me there,
that 4th blade does wonders for some loads, though, and if you are running heavy, especially in the bow, that 4th blade can really make a great difference.
I did PM you back on some other things as well, and I think you've got a few things to tinker with, but overall, I think we can find the issue and you will have a very quick and efficient running rig. That size of boat should have you mid 30's.
Steve |
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Posts: 410
Location: Wakefield, MI | My dad's Bass Tracker Pro 17 with a 40hp Mariner does 26 mph on the GPS, I think it's on the 2nd hole and a 3 blade prop, don't know the rest of the info (could probably run over there and get it for you if I know where to look). That's loaded down with musky gear and me and my dad (both overweight). The tach isn't working right so don't know the RPM. |
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Posts: 1316
Location: Lebanon,Mo | I can give you lots of info/some specs on your 40hp performance needs if you call me sometime. I have been with a 40hp motor with five different boats the last ten years. I fish a lake with 40hp limit and pretty much stuck with it.PM me with a number or will leave mine...
Fred
Edited by missourimuskyhunter 7/30/2012 8:53 AM
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Posts: 1
| Just for reference. My 14' aluminum V-vull does 23.5mph with a Mercury 15HP four stroke. (2) 200lb guys and fishing gear.
A 40 HP Mariner on a Bass Tracker 17, doing under 28mph, is just bad. Motor is either sick, or setup wrong IMO. |
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Posts: 416
Location: Madtown, WI | I had a 2S 40hp on a light 16' aluminum boat (Misty River DLX1600) with 72" beam, top speed was 27mph. I repowered to a 60hp and top speed is now 33mph. |
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| got a 16 ft trihull with a 50 erude does 27mph, the pitch is 15 |
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Posts: 202
Location: Angola, IN | VMS - 7/29/2012 7:36 PM
The 14 pitch in a 4 blade would be a little harder to turn than a 3 blade 15, so that makes some sense to me there,
Steve
It's the 4 blade that's hurting you. Get a 3 blade 15 or 17 pitch around the 12" range. 15 if you have to get one a touch over 12". But with that older motor, I see no reason to run it WOT at max RPM's. Seems kinda silly. Put so much more extra wear and tear on that old motor.
If I was you, I'd get a 3-blade 17 and be done with it. Max out at 5.1-5.2k and be happy. I'd be happy with 5k honestly.
I keep my old 115HP Johnson at 4k for a reason. |
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