lower unit choices

[1987 175 mercury]

I have a 18.5 1987 stratos vt rocket with the factory 175 that came on it.thru some tlc it runs great.set up with a 4 blade prop.I am know addressing another issue that i bought it with.The skeg had been broken off at the ramp by the previous owner.He had a skeg cover on it and that was fine until the time came to fix it.Now is that time.I have water pump issues.The boat always wanted to idle hot,as soon as i jumped on plane it would cool.I live in south florida and run shallow and get on plane shallow.My initial thoughts were to have the lower unit taken apart,weld on a new skeg,re-seal and put lower unit back together,making repairs on the water pump issues all at the same time.Since the tunnel hull of the boat is probably going to give me the ability to raise the engine to a higher mounting and i need shallow water capabilities are there other options that would allow me to gain those needs on similiar expenses that repairing my existing would be.Possibly fixing my hot idle issues and allowing me to have additional water pick up when running the engine high.Any ideas on a different lower unit or avenues to gain more knowledge on these issues would be appreciated.Also info on setting up my engine height with this hull.THANKS!

 

[Faztbullet]

Re: lower unit choices

That a pretty good hull and removing windshield will add about 5 mph to top end as it act as a elevator and hold bow down. Also that hull has to reach at least 60 mph before the tunnels start to become effective. The 175 you have is a chrome bore 2.4 liter with vertical reeds. I set several of these up when they first came out and if you want just speed here is the setup: 4 inch jackplate that will give you a total of 16" setback due to stepped hull, top 3water intake holes plugged on each side lower unit,cavation plate set 2-1/2 inches" above bottom of pad, 24 pitch cut down big ear chopper or Trition 2 14.5 X 22 , water pressure guage, new jetting update and dont turn it over 6200rpm as the hp/torque falls off after 6200rpm. For the hot issues ensure the poppet valveis in working order ,t-stats are in place and impeller and housing are in good shape.

 

[1987 175 mercury]

Re: lower unit choices

THANKS for the reply.The boat is set up now with a hijacker jack plate measuring the set back is 5 inches.I will move the engine according to instruction.The lake that I fish is an extremely open body of water and can get rough.Do you recomend different props or different motor heigth to try and get the best of both worlds in speed and ability to handle rough water or just a difference in my trim?On your advice with the chopper prop how much would you recommend cutting it down?Thanks again.

 

[1987 175 mercury]

Re: lower unit choices

More follow up on your reply.Began some research on you big ear chopper advice.Have found several choices and am asking for advice on the prop.The pitch 22,24,26,28?The different designs A5 or SS?Continued knowledge on this would be apreciated also.Thanks.

 

[Faztbullet]

Re: lower unit choices

Any prop shop worth its weigh will know how to cut-down a big ear chopper, it will look like picture below. If you ski or tube this setup is not for you. Also add a set of trim extenders as you will need the extra positive trim to "fly" this hull(see pic below). With a perfect set-up you will be pushing 62-67 mph if boat is not saturated with water...

 

[1987 175 mercury]

Re: lower unit choices

Thanks again for the reply and pics.Thats nice.My boat is the bass boat version.The hull is very dry did not have those issues yet.Will not ski or tube much if ever with it.

 

[1987 175 mercury]

Re: lower unit choices

Thanks for the reply and pics.If you have any advice on repairing my skeg on lower unit that would be apreciated also.When you discussed removing the windshield was that in reference to the ski version of the vtrocket or the bass boat version as I have the bass boat version.THANKS AGAIN!

 

[Faztbullet]

Re: lower unit choices

Ski version and post a pic of damage. You can buy the replacement skeg($25) here on iBoats and have a welder cleanup and reattach it if not to badly damaged.
http://www.iboats.com/T-H-Marine-Re...11214437--**********.704264516--view_id.40152