Lossing speed #2

This topic has 9 replies, 4 voices, and was last updated 13 years, 7 months ago by ischnell.

Viewing 10 posts - 1 through 10 (of 10 total)

Author

Posts
November 14, 2012 at 12:52 pm #305576

captain action
Participant

last time I wrote was 10/26 about losing top end. Heres the #s with the new prop. Empteyd all my tackle storage lockers,25 gallons fuel, 4 31 series batterys, Im 210pounds, and the motor is set at factory height on jack plate. 2010 ftd puma, 250 pro xs merc. new prop ran 78 mph, rpms 5930,put the old reworked prop on,ran 78 mph at 6130 rpms. Can someone share whats going on and help exsplain what the #s mean and tell me the ratio of speed to weight lost per 100 lbs. added? what should my puma run at full tx. load and can I reach that #. THANKS!

November 14, 2012 at 1:00 pm #305577

Bass Cat Boats
Keymaster

This speed is within the expected range, the low end. It is hard to say what the situation is and why it may be loosing performance.

November 14, 2012 at 2:46 pm #305578

captain action
Participant

Please bcb, why cant I get answers to this post? What can you tell me about the motor running at 6130 rpms, is this ok?, will it blow it up? whats causing the 200 rpm difference in props but still the same 78 mph, Can anybudy with a 2010 puma ftd 250 xp on a manual jack plate give me there number. Icant find a 2010 250xp for sale on the site to see there numbers to compare, PLEASE I”m losing it guys.

November 14, 2012 at 3:01 pm #305579

ischnell
Participant

Ok I will try Your 2 different props are different the engine is putting out a certain amount of power through a range of RPMs Therefore it is possible that you get the same speed at different RPMs it sounds likethe new prop has more bite thatn the old one, I dont think you will harm the motor because I believe that motor has a 6200 RPM limiter. As to your overall speed you need to look at setup, try several different jackplate settings either higher or lower etc. You are fairly close to the potential of that boat 2-4 MPH can easily be lost in setup and in my experience no two hulls react identically to all props and settings. Try giving more information. Type and pitch of props used, pad to centerline thrust measurement. I assume you are using GPS speed numbers also.Irv

November 14, 2012 at 6:27 pm #305580

Bass Cat Boats
Keymaster

What prop was this? I have 2 26 fury that run about the difference your talking about(rpm) . Actually the lower rpm prop is faster/ has more bite. I run 78 loaded ( full gas, 2 folks, gear for three, etc) in dog days. Cooler months I run 80ish loaded. Turned 82.8 couple weeks ago on lay( gas an livewells full) solo. My partners best speed is bout 77 when he is driving. My boat doesnt seem to be very weight affected, have run 77.8 with 3 people in it. What lower unit do you have?

November 14, 2012 at 7:11 pm #305581

Bass Cat Boats
Keymaster

We really dont comment on the engines as we are not an engine company to offer an opinion, if the RPMs are in the suggested window then we think your good. The suggestion we have is to lower it some and try to gain some bite in the propeller.Anything beyond this is speculation as we can not see, feel and touch this rig. BCB

November 14, 2012 at 8:24 pm #305582

captain action
Participant

Both props are 26 furys, new prop empty lockers 78 mph on gps and 5930 on the smart craft tac. 2nd prop is a 26 fury that i dinged and had fixed, same load boat ran 78 mph on gps and 6120 on the tac

November 14, 2012 at 8:28 pm #305583

captain action
Participant

motor is 2010 250 pro xs, I was told its the tourq master

November 14, 2012 at 11:04 pm #305584

TXUex
Participant

run the figures on this prop slip calcalator(http://www.rbbi.com/folders/prop/propcalc.htm) and it shows approx 6.5% slip on the prop that turns 5930.The prop that turns 6120 shows 9.4% slip. Both of those numbers are good, in fact the 6.5% is really too good. Usually somewhere between 8% and10% are the best you can expect. I used 1.75 as the LU gear ratio which is what I think the TM is. Since I dont have a new enough motor to havemy Smartcraft indicate speed, I have to ask if this is GPS or water pressure speedo. If it is not actual GPS numbers then the 78 mph is not correct andall of this is just speculation. Oh yeah your motor does have a 6200 rpm rev limiter chip so it will tell you when you when you rev too much by killingcylinders to keep the motor from over revving.Johnny

November 14, 2012 at 11:18 pm #305585

ischnell
Participant

using your new prop try raising the engine a 1/4″ at a time while watching GPS speeds, if they go up while retaing water pressure your good to go. If they go down then lower 1/4″ at a time watching GPS speed you will eventually find a happy point for you. the only other way would be to get someone experienced with boat setting up to play with your rig and get it fine tuned. Also be sure the motor is all correct as far as throttle opening etc.Irv
Author

Posts

Viewing 10 posts - 1 through 10 (of 10 total)

You must be logged in to reply to this topic. Login Register