Heavier GF16 having trouble getting on plane

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TomW1
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Re: Heavier GF16 having trouble getting on plane

Post by TomW1 »

Andrew I am starting to see a lot of problems for why you cannot get up on plane with your GF16. First is all the weight on your transom with the trolling motor and I assume its battery near it. Mount it on the bow or get rid of it for now. Your Merc can troll at 2-4 mph. Get a tach so you can tell that you are down at low enough rpm's. You need to balance the weight on the stern and the weight on the bow. On the GF16 I was on the Battery and gas tank were under the center seat. The easiest way to do this is add all the weight you have on the stern and how much you have in the bow. Then try to distribute it. I do not know where the Longitudinal Center of Gravity is on the GF16 but probably about the center seat so all weight should be distributed ahead of and behind that point. Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

AndrewS
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Re: Heavier GF16 having trouble getting on plane

Post by AndrewS »

So the boat + trailer weighs 1060lbs, the trailer isn't listed on academy's website anymore and I think it weighs around 220 lbs. Weather permitting I will be taking it out tomorrow morning to get the RPM reading.

TomW1
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Re: Heavier GF16 having trouble getting on plane

Post by TomW1 »

Andrew there should be a tag on trailer, metal or paper giving the weight of the trailer and tare weight. Tom
Last edited by Jaysen on Sun Sep 18, 2022 12:59 pm, edited 1 time in total.
Reason: Corrected html formatting error.
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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Re: Heavier GF16 having trouble getting on plane

Post by AndrewS »

TomW1 wrote: Sun Sep 18, 2022 11:53 am Andrew there should be a tag on trailer, metal or paper giving the weight of the trailer and tare weight. Tom
Hey Tom, there is a tag but does not list the weight of the trailer only the max weight allowed. I won't be able to get out to get the RPMs till next week. I think I might move the trolling motor battery up to where the 2 house batteries are and remove them.

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Re: Heavier GF16 having trouble getting on plane

Post by pee wee »

If you know the model number of the trailer, there is a way to look at archived Academy Sport pages and look it up there. I'm no expert, but I've gone to archive.org and used their "wayback machine" (I think they got the name from the old Rocky and Bullwinkle/Peabody's Improbable History cartoon!) to look at old web pages.
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Re: Heavier GF16 having trouble getting on plane

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AndrewS wrote: Tue Sep 20, 2022 9:25 pm
TomW1 wrote: Sun Sep 18, 2022 11:53 am Andrew there should be a tag on trailer, metal or paper giving the weight of the trailer and tare weight. Tom
Hey Tom, there is a tag but does not list the weight of the trailer only the max weight allowed. I won't be able to get out to get the RPMs till next week. I think I might move the trolling motor battery up to where the 2 house batteries are and remove them.
Where are the house batteries now if under the center seat don't remove them, they are helping you right now. Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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OlivierP
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Re: Heavier GF16 having trouble getting on plane

Post by OlivierP »

Definitely moving weight forward is the way to go.

I have a GF14 (about the same weight as the GF16) with a trolling motor and big lead battery on/under the front deck ; I have installed remote controls and sit on the middle bench. It goes on plane instantly with a 9.9hp. Not fast (16kts top) but no issue with going on plane.
Built C17 (app.php/gallery/album/262), GF14, Devlin Bella 16. Sails a 30ft Biloup 89 sailboat.

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Re: Heavier GF16 having trouble getting on plane

Post by AndrewS »

boat batteries.jpg
I was finally able to make it out today with the tach. The first time I went WOT I was able to get on plane but not any time after that. My RPMs were at 5100-5300.

I was thinking of moving the trolling motor battery up where the house batteries are and just using the one battery for everything. Up front in the bow I have 2 3gal gas tanks.

fallguy1000
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Re: Heavier GF16 having trouble getting on plane

Post by fallguy1000 »

Well, there you have it. You are not achieving wide open throttle, time for a new prop!

Get the right engine specs, but I see 5700-6200 for the current Merc 2022 four stroke 20 hp engine.

So if you only got to 5300; you are at least 500 rpms away from spec. This means you are running about 10% below rated power, or if you push to 6000, 700 more rpms divided by 5300 is almost 15%! Once up and over the hump; you might even be able to back down a bit.

But the engine is a bit undersized in any final analysis.
Last edited by fallguy1000 on Sun Oct 02, 2022 2:37 pm, edited 2 times in total.
My boat build is here -------->

viewtopic.php?f=12&t=62495

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OlivierP
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Re: Heavier GF16 having trouble getting on plane

Post by OlivierP »

If you haven't already, try sitting on the middle bench with a long tiller extension. On a small boat the pilot is the first weight to move around...
Built C17 (app.php/gallery/album/262), GF14, Devlin Bella 16. Sails a 30ft Biloup 89 sailboat.

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