1973 50hp Merc planing issues

[chris16371]

I have an excellent running 1973 50hp Merc 4cly that I can't get to plane a 1977 Ozark T163 Sport Fisherman. I have only had boat out once a week ago and the motor moves the boat pretty good and the boat isn't waterlogged. I have tried every pin hole and I can't seem to get the bow down with me 165#, my fiance 130#, and my German Shepherd 80#. I may just simply be underpowered with the boat being able to handle up to 115hp. I was just seeing if anyone can give me advice on how to maybe to get the boat to plane with the current motor. When I get out of work I'll check my prop pitch, I have a couple extra props both bigger and smaller as well.

It's not a huge deal since we are just usually going to be trolling the Allegheny Reservoir but if it's a little ways from where we launch to where we want to fish it would be nice to be able to get there faster and the right way, on plane! The tri hull has a side console and is open everywhere else so I really like the space in it but I prefer fishing the Allegheny River so we are highly considering buying within the next month a Lowe L1648 MT Aura with a side console, live well, and a 40/29 outboard jet. If we go this route we will be able to use the jet boat on the river or reservoir so we would just sell our other boats but I would like to sell the tri hull operating the way it should so it has some importance. There's also an option of just buying a jet foot for the Merc making it a 50/35 and if I went that route I would find a used 80+ hp motor to put on the tri hull to sell with it.

Anyways, Ik I ramble a lot, we will be going out this weekend so was hoping for some tips for getting this boat on plane. Thanks!

 

[Chinewalker]

Boat should plane off if motor is running properly and propped correctly. Motor should be peaking in the 5000-5500 range at wide open. If someone threw a prop with too much pitch on there, it would be like trying to drive your car uphill, towing a trailer, in high gear. With a boat of that size, I would think you should have an 11-inch pitch prop or somewhere thereabouts. Take a look at the prop hub, either by the prop nut or on the side, for any numbers and report back.

 

[Sea Rider]

Without a tach reading on what was the max wot rpm achieved as loaded won't know if current prop is right for that combo or which pitch is needed to pull wot revs up as seem needs.

For the moment untill a tach is installed, with engine trim set at neutral, fiancee and dog sitting up front, go full throttle and check if combo planes out. If not prop could be on its way to be, it's already spun or over propped. Get an induction Hardline or TT tach.

Happy Boating

 

[chris16371]

Numbers are a little worn on the prop but I believe it says 10 1/4x18. I have the factory tach for the motor but forgot to install it and left it at home unfortunately, I'll put it on before I go out again. Does the tach plug right into the controls? It looks like there's a male end on the front of the controls that the female plug from the tach goes into but I just want to be sure.

 

[jimmbo]

I don't think mercury made an 18" for the 50hp. check again, maybe that 18 is 13.

 

[chris16371]

Like I said numbers are kinda hard to read, 13 is probably right but I'll double check. I have to check my other props that came with it also to see if I have a smaller pitch.

 

[Chinewalker]

Gut feeling is that 13 is a little on the tall side. Try an 11 if you have one. As noted above, a tach is very helpful in getting things set correctly and will tell you if the motor is even reaching it's recommended top end...