polar skiff 1796 won't plane

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Swampcreek
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polar skiff 1796 won't plane

Post by Swampcreek »

I just got this skiff and do not know much about it. It is used. It has an 75 mariner 1989 model i believe. Compression is over 100 on all three cylinders. I dropped it off at my mechanic to go through the carbs. It sounds like it is running ok. It has a stainless steel prop, dont know what size. (big) I'm guessing a 13 pitch 3 blade.

When I give it WOT the nose goes up and doesn't want to drop at all. The engine doesn't rev up too high like its too much. I was thinking weight was my problem. My big arse sat on the bow and nothing happened. It probably only went 5-10 mph. Any ideas ?
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Re: polar skiff 1796 won't plane

Post by SCALAWAG »

Does it have tilt and trim? if so are you trimming it all the way down
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Steve Stinson
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Re: polar skiff 1796 won't plane

Post by Steve Stinson »

On those old Mercury / Mariner motors, the power packs (coils) will go out sometimes causing the symptoms you are describing. Based on your description of the prop, I don't believe it is over-propped. Do you have any idea if the boat ran okay in the past as it is currently set up?

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Re: polar skiff 1796 won't plane

Post by Steve Stinson »

When you have the motor in a strain, does it make a popping sound like some of the cylinders are misfiring?

If so, you have an electrical problem like I described in my previous post. Crank the motor on the hose and let it idle. With rubber coated pliers, remove and replace the plug wires one at a time. (You will only do this once standing in all that water without the rubber coated pliers) :-D . If you pull a plug wire and the rpm's of the motor do NOT change, that cylinder is the one with the problem. Could be the power pack, plug, or plug wire.

If you get a smooth fluctuation in rpm's when the motor is in a strain (no sudden popping), your problem is likely fuel supply, dirty carbs or bad fuel. If you have a clean six gallon boat tank, go fill it with fresh non-ethanol fuel and plumb it directly into the motor. This should fix anything except the dirty carbs.

Hope this helps. If all else fails, take it Waivel Porter down in Woodville. He will gripe at you for owning a Mercury product, tell you it's going to be about a week, then fix it in a couple days for about half what some others charge. :thumbup:

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Re: polar skiff 1796 won't plane

Post by FUTCHCAIRO »

YOU MIGHT WANT TO CHECK THE BOTTOM OF YOUR BOAT, IF IT HAS ABOUT 1 INCH OF BARNICLES ATTACHED TO THE BOAT THAT WILL PUT ABOUT 1.000 POUNDS OF DEAD WEIGHT OF LIVE BARNICLES. I HAD A BOAT BROUGHT IN FOR ME TO WORK ON BECAUSE IT WOULD NOT PLANE, WAS NOTHING WRONG WITH THE ENGINE, JUST HAD 1,100 POUNDS OF LIVE BARNICLES, I SCRAPED THE BARNICLES INTO SOME 5 GAL. CANS AND WEIGHED THEM, TOOK ALMOST A FULL DAY TO GET ALL OF THOSE BARNICLES OFF THAT HULL AND FOOT OF THE ENGINE. THE BOAT PLANED JUST FINE AFTER THIS. THERE ARE SEVERAL HUNDRED THINGS THAT WILL CAUSE THIS, JUST HAVE TO CHECK ONE THING AT A TIME TILL YA FIND THE PROBLEM.
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cheekatall
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Re: polar skiff 1796 won't plane

Post by cheekatall »

Just replaced the 2 power packs on my Suzuki, solved the same type symptom. Could not get mine over 3,000 rpm's at full throttle. You can try disconnection the leads to the plugs while the engine is off preferably, may have to do it in pairs, if your packs feed to the spark plugs to see if the engine runs the same, worse or run at all to help isolate it to the power pack and which one, if that's happens to be the problem.
rickc
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Re: polar skiff 1796 won't plane

Post by rickc »

Swampcreek wrote:I just got this skiff and do not know much about it. It is used. It has an 75 mariner 1989 model i believe. Compression is over 100 on all three cylinders. I dropped it off at my mechanic to go through the carbs. It sounds like it is running ok. It has a stainless steel prop, dont know what size. (big) I'm guessing a 13 pitch 3 blade.

When I give it WOT the nose goes up and doesn't want to drop at all. The engine doesn't rev up too high like its too much. I was thinking weight was my problem. My big arse sat on the bow and nothing happened. It probably only went 5-10 mph. Any ideas ?
i had one. didn't realize that there was a drain for the inner hull. drained the water out and it was faster and floated shallower.
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Re: polar skiff 1796 won't plane

Post by Steve Stinson »

Sheesh. I didn't even think of that one. Of course, if the hull is full of water you won't plane off and the boat will lean precariously if you don't stay right near the centerline of the hull.

Post an update so we know how this mystery works out.

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Swampcreek
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Re: polar skiff 1796 won't plane

Post by Swampcreek »

I sent it to the mechanic. I gotta have a hip replacement tomorrow, so I will worry with it when I get back on my feet. I took all the plugs out and no water came out of the inner hull. He is redoing the carbs. Said it was a good motor. I was worried because I have read that those hulls can get water logged easily. But I don't think I can check that without taking the hull apart. The boat is in good shape, no soft spots that I can find. No barnacles. I hope it's just in the carbs.

I will let ya know what happens. Just wanted some ideas to look for. Hopefully I will see ya'll on the water sooner than later.
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Swampcreek
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Re: polar skiff 1796 won't plane

Post by Swampcreek »

The guy I bought it from mentioned the bow riding high. He used it as an oyster boat, Id imagine he didn't have that problem with a bunch of weight on the bow. He said he went through the carbs and water impeller/pump. I don't take people on their word much. It wasn't peeing like it should, even with the thermostat out.
UFBeef
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Re: polar skiff 1796 won't plane

Post by UFBeef »

What rpms are you hitting at wot? If you are concerned about the hull being water logged, take it to a set of scales and weigh it. You can figure about what it should weigh by the manufacturer's specs on the hull, motor and aguestimate on fuel and additions.
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Swampcreek
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Re: polar skiff 1796 won't plane

Post by Swampcreek »

I finally got to run it again since the carbs, impeller, splugs and wires were changed. Still won't plane out. Any one know of a guy that will take it out on the water and fix it without breaking the bank?

I'm thinking it may be the prop but I am now clueless. I don't think it is water logged.
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Re: polar skiff 1796 won't plane

Post by Steve Stinson »

Waivel Porter - Porter Marine in Woodville.

The only suggestions I have at this point are -
1. Borrow a smaller pitch prop the same or smaller diameter and try switching them out. I don't believe that motor you have should struggle to turn a 13 pitch prop, so I am not confident this will lead anywhere.
2. Check the power packs. Those old Mercury's had a power pack (coil) for each cylinder. If one goes down, it can cause the symptoms you are having. I would think your mechanic would have already thought of this, but perhaps not.

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Swampcreek
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Re: polar skiff 1796 won't plane

Post by Swampcreek »

The only marking on my prop are 7049 so i have no idea what is on it
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Swampcreek
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Re: polar skiff 1796 won't plane

Post by Swampcreek »

Update : changed the prop to an aluminum 13 pitch and it finally leveled out. It takes a long stretch to do it. I'm going to put some new cables on all the controls and see if it helps. Other than that, I would like to put a 90 HP 4 stroke on it, but my wallet wont let me.
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