Bass Fishing HomeBass Fishing Forums

Go Back   BassFishin.Com Forums > Serious Conversation Only > Bass Boats, Trailers & Setups

Reply
 
Thread Tools Rate Thread Display Modes
Old 04-16-16, 10:03 PM   #1
MO_CPA
BassFishin.Com Active Member
 
Join Date: Jun 2011
Location: Ozark, Missouri
Posts: 361
Default Prop Question

Good day gents,

So I have a Tracker 175 TXW with a 60HP Mercury 4 stroke. I had a 3-blade 10.375 x 14P prop on it and it was a DOG coming out of the hull when I had two guys in it and a normal fishing load of gear. When I say dog I mean 10+ seconds to plane.

Since this wasn't quite good enough for me (thinking it was somewhat of a safety hazzard) I switched to Mercury's new Spitfire aluminum 4-blade in a 10.3 x 13P. I tell you what, it's like I added an extra 50hp back there...the hull shot was improved by at least 50% and probably more (4-5 seconds with two guys and gear). The boat just handles all around better, turns better, trims better, reverses better, and etc.

Here's where the quandary is, I now reach the top of my manufacturer's rpm range much quicker than I did before (6,000 rpm). I hadn't lost much if any top-end performance but I get to the top before I have laid the hammer all the way down. If I do lay it down, the rpms will get all the way to 6200 rpm give or take.

So, should I be concerned or should I just be mindful of my tach and not over rev it? I'm concerned if I pop up to a 14 pitch 4 blade I will lose my new-found hull shot and performance improvements that I am so in love with. This boat is not a speed demon by any means, so should I just be happy with what I have?

Thanks for the input.

MO
__________________
Whatever you allow is what will continue.
MO_CPA is offline   Reply With Quote
Old 04-18-16, 07:39 AM   #2
mikechell
BassFishin.Com Active Member
 
Join Date: Apr 2011
Posts: 464
Default

Propping has always been a balance of hole shot and top end.
Less pitch (or diameter) on the prop: get faster revs and better hole shot, but you lose top end speed.
More pitch: you get more top end speed at the expense of the hole shot.
The main variable you need to be careful of is the rev limiter. (you cannot actually "over-rev" a modern day engine).
If you are getting to max RPM too quickly and hitting the rev limiter, you have too little prop. You can (rarely) cause damage if you're continually bouncing off the rev limiter.
If you aren't actually getting to the rev limiter, then you are propped perfectly ... best hole shot and best top end.
mikechell is offline   Reply With Quote
Old 04-18-16, 09:33 AM   #3
mikechell
BassFishin.Com Active Member
 
Join Date: Apr 2011
Posts: 464
Default

When my guys are setting up a new boat, I always have them prop a boat to HIT the rev limiter at top speed.
That boat will NEVER be as light as it is right then. The customer will immediately fill the fuel tank to the top (63 pounds per 10 gallons), put in a few items (gear, life vests, coolers maybe) and one to several people. All these additional weights will bring the RPMs lower and lower at WOT.
It sounds like your original prop was set for "proper" RPM with one person and no extra weight onboard.
mikechell is offline   Reply With Quote
Old 04-18-16, 12:46 PM   #4
MO_CPA
BassFishin.Com Active Member
 
Join Date: Jun 2011
Location: Ozark, Missouri
Posts: 361
Default

Thanks for the info Mikechell.

I never hit the rev limiter, even trimmed out and hammered down. I did jump over the manufacturer's recommended RPM's per my tach by 200rpm. I pulled it back quickly in fear that I would damage something.

Another thing to think of, it was relatively cool yesterday and very low humidity. I heard that the motor will run less RPM's in hot sticky weather, which is normally what I fish in.

The other thing that might be changing my RPMs is the fact that I can trim much more with the four blade than I could with the three blade without porpoising.

I think I will stay where I am at. The boat is running well, just very different. It will take some getting used to.
__________________
Whatever you allow is what will continue.
MO_CPA is offline   Reply With Quote
Old 04-19-16, 11:43 AM   #5
Captmikestarrett
BassFishin.Com Super Veteran
 
Captmikestarrett's Avatar
 
Join Date: May 2006
Location: Accokeek MD
Posts: 3,306
Default

This is good info.. It makes me think of something my dad explained to me while on an Air Force C130. The turbo prop and how it feathers the blades to achieve lift off and then air speed. The blades rotate to adjust pitch.. So some time ago a Mercury tech put together a prop that does just that.

http://www.saltwatersportsman.com/me...-new-smartprop

They got mixed reviews at first but as the design got better the prop got better.

Capt Mike
__________________
Capt Mike Starrett light tackle guide Potomac River
http://www.indianheadcharters.com
Captmikestarrett is offline   Reply With Quote
Old 04-20-16, 01:09 PM   #6
mikechell
BassFishin.Com Active Member
 
Join Date: Apr 2011
Posts: 464
Default

Funny you should bring that up, Captain. The first aircraft I worked on in the Marine Corps was the C-130. You are correct about that AC ... the engines are maintained at about 90% full speed and the props are angled to get whatever performance is desired. Take off required about 110% from the engines (very easy to do, short term, with a jet engine) and max pitch on the props. Or they used JATO ... which was a fantastic kick in the pants on the bird, very cool to watch from the ground.

Mercury's variable pitch prop is no longer made. It was great for heavy boats, not so much for the average "joe".
mikechell is offline   Reply With Quote
Reply

Disclosure / Disclaimer
Before acting on the content posted, you should know that BassFishin.Com may benefit financially and otherwise from content, advertising, links or otherwise from anything you click on, read, or look at on our website. Click here to read our Disclosure Policy and Disclaimer.


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 11:44 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
2013 BassFishin.Com LLC