ski pole issue

Hi guys,
I have a question for those of you in the know. I have a ski boat that has a ski pole mounted at the rear of the boat and when I try to pull kneeboarders or tubers it damn near sinks the boat ( I dont pull skiiers as I dont ski )... it pulls the back of the boat down so far it would put the boat on almost a 45' angle... which is kind of scary really. When I use a bridle on the transom tow points it seems fine but the pole is a worry.

A little background on the boat. I have rebuilt almost everything on this boat given the confidence and information I gained from these forums and I thank you guys whole heartedly for that. I replaced the transom, floor, bilge area and even the nose section. This was required after getting bad advice from a relative that this boat was solid.. when I purchased the boat it had a 78' 140hp Chrysler outboard on it, and when I removed added on items in the boat I discovered the hull was only rated to 115hp. So I have since put on a 1979 115hp mercury tower of power which is fantastic. When I had the ski pole on the boat with the Chrysler I didnt have these issues but now its quite scary. The boat wont plane and I am seriously concerned to give it more throttle than I have with the ski pole in use because it really bogs down even to the point where at one time the prop was exposed from the water and revved like I had spun the rubber bush (which it had not) the prop is a 13 1/4" 17p. the boat is 15 ft long with the 50L fuel tank at the front and back to back seats. and it does struggle to plane at speeds under 20-25 mph. Anyway if you guys could please dip into your knowledge banks and help me with either of these issues it would be much appreciated as it is a worry.

Re: ski pole issue

So two things... You replaced the floor, how was the foam under it? The second is that you aren't using trim? It sounds like either it isn't being used, or maybe the boat doesn't have trim? Your motor is way too high, you need to trim it down, and as you come up on plane, ease the trim up some. This becomes more important when you are pulling someone, as you found out.

Re: ski pole issue

Sure sounds like the motor is trimmed out too far. So, two things have changed - you rebuilt the transom and you changed the motor. There is a problem with one of those. Assuming the transom is straight and true (???) then you need to adjust the trim settings on the motor.

Re: ski pole issue

+3, sure sounds like motor is either mounted too high or needs trimmed down, or both. That 115 OB is fine for basic skiing and tubing, unless you are trying to haul up a 225lb slalom skier or multiple person oversized tube.

Re: ski pole issue

Also, don't ever tow tubes from the ski pylon. You could load up the line if the tube digs it, and you've created a slingshot/projectile. The pylon is fine for the wakeboard/ski/kneeboard though. I would do as the others suggest and start looking at trim/cavitation plate height, etc to get the boat operating as it should. The pylon should make little difference in the running characteristics.

Re: ski pole issue

You mentioned the HP rating however I will bet there is a weight limit on the power plant too. And that tower of power may weigh more than your previous Chrysler even though it's less HP. How much weight difference do you have? It may be contributing to how the bow operates. Are you trimming down full for your hole shot then backing it away from full down once plane is achieved?

Re: ski pole issue

A ski pylon tall enough to clear a 6-cylinder Merc. is a tall pylon.
A 15' boat is not a long nor probably very heavy boat.

My experience having owned 15' and 16' boats with outboards (even with OMC V4s) and a few different pylons, is that there can be enough leverage from the high tow point that on hole shot, the bow rises, and the boat is slower to plane or with enough load will not get on plane. You say the back of the boat is "pulled down." Front of the boat levered up is the same net effect. (unless the transom is sinking which I doubt). Especially since you say it is fine when towing from the transom eyes.

Yes, as others have said, make sure you have your trim all the way down, but I would recommend just towing from the transom eyes with a bridle unless you have a very light skier. I added transom wedges to one boat (between transom and outboard motor brackets...thick-side at top) for greater negative trim that REALLY was great for slow-speed skiing and pulling tubes and kneeboard. My 16' boat would come up and be on level plane at about 13 mph which was great for the kids where 14-15 mph was fast enough for them to ski when they first started. And it allowed me to use the pylon for all but my bigger friends (200 lb plus) getting up on a slalom ski. I still didn't use it for pulling tubes.

Solution: Get a Sawzall and cut the top three cylinders off the Merc and shorten up your pylon by 12" or just don't use the pylon. Or you might try some transom wedges: T&H Marine TW2DP Transom Wedges*-*T&H Marine*TW2DP - Motor Accessories - Boats/Boat Motors - Boatersland Marine