Power options for Sun Tracker Party Barge 20

I have a Sun Tracker Party Barge 20 with a Mercury 60 four stroke big foot outboard. I'd like to put a larger engine on it for improved performance for tubing and water skiing. Max power placard says 115. The dealer I'm talking to says if I put a Mercury 115 on it, I'd need to add hydraulic steering, a $2100 option. Does anyone have any data to support or deny this recommendation?

I have a 16dv with a 90 on it and am glad I have hydro steering, 115 could be tough with just the teleflex cable. might consider with the upgrades getting a new boat, the tri toons with the 3.0l MPI's go pretty good or look at a deck boat with a 350 mag with a bravo 3 ?

A 115 is getting "close" to where you want hyrdraulic steering and as noted above it's really nice to have, but you can realistically use cable steering upto/including about 150 horses of outboard power. I run a 140 (V4 Evinrude) with a single cable system (Uflex rotary) and it works ok. Teleflex produces a dual cable/no feedback system which might overcome some of the perceived "torque" on the steering or you could find another dealer and ask about a "Baystar" hydraulic system which is suitable for that horsepower and should come in around the 1000 buck mark installed (the option I am considering for myself when the steering cable needs changing).

Have you got some realistic advice/answers about what kind of performance improvement you could see emptying your wallet with these upgrades?

Older pontoons were never meant to "go fast". Upgrading from a 60 bigfoot to a 115 (4 stroke EFI I assume) might net you as little as 5 more mph at wide open (and probably not more than 8 mph even under perfect conditions).

The 115 weighs in about 140 pounds more, just for starters (like carrying an extra ***** on board all the time, so you lose maybe 15 or 20 of those extra horses just to push the added weight of the new motor), so count on burning almost double the gas that you currently do (so maybe a larger tank is in order as well, which adds cost and more weight still, that further takes away from the "speed gain" - gas weighs about 6 lbs per gallon).

Sometimes things just "are what they are" - if you want a watersports boat you really might be better off selling what you have and buying one. You could spend alot of money on upgrades for what you currently have and still be disappointed with the performance...

gl115 & galamb, thanks for your replies. My toon is a 2011 model. Alone in my boat (with a trolling motor, battery, anchor, and around 20 gallons of gas), I get 18 mph max speed - add 3 passengers and pulling a 7-year-old on a tube, the speed dropped to 12 mph (measured on my gps). I did a test drive on a 2011 21 foot model with a 90 on it and got considerably better performance. With a salesman, my wife, and I, we got 28 mph. According to the Mercury marine website, the 90 and the 115 weigh the same and are actually the same motor with some fuel system differences. I understand the big foot lower unit and prop on my 60 is really a 115 lower unit and prop.

Obviously, I'm trying to gather data and opinions from experienced and knowledgeable folks like you before spending a lot of money on a performance-oriented upgrade.

Thanks - Castor

You might be comparing apples and oranges with the 21 footer you tested. If the pontoons had lift strakes or were otherwise "different" than your particular model then they will not compare. There is a whole line of "planing" toons out there now that were build for speed (albeit with higher horsepower).

The general rule of thumb for a given hull is - you must increase the horsepower by 50% to get a 15% top end speed increase.

From your numbers - 18 mph with a 60 you would see (theoretically) about 21 mph with 90 horses and maybe 24 mph with a 120 (115 or 125 - close enough) however you have to factor the extra engine weight (about the same as another person on board - 140'ish pounds) which will shave one/two mph from results.

So at 12 mph "loaded and towing", with a big foot that is designed to pull the weight without "bogging", the best you could hope for is maybe 16 mph, and probably not even that because you would have to run less prop pitch, even though you have more horses, to compensate for the higher gears on the 115 and the extra weight of the motor.

Some of the new 'toons really can "boogie", others are still just a dock with an outboard strapped on the back.

I would really investigate what type you have before you open your wallet any further...

how many RPM's are you going at WOT? might just be propped wrong for your application and just need a new prop.

Getting about 5400 rpm WOT. Prop has a number stamped on the side that's difficult to read, but I believe it ends in
11p15. I presume that's pitch & diameter. Am I right with my information that a "Big Foot" on a 60 is the same lower unit, gear ratio, prop, etc that's on the 90's and 115's? The boat I test drove had the same pontoon tubes as mine, but a different seating configuration and a foot longer deck. I saw it on a trailer and didn't notice any lift strakes. On the boat packages from Sun Tracker that offer 90's and 115's as optional motors, the 115 is $1000 more than the 90. I don't see any way that can include hydraulic steering.

5400 sounds about right,

If anyone's interested, I ended up buying a Merc 90 4 stroke and am extremely pleased with it. Top speed increased from 18 to 28 mph (measured on my gps), rpm increased from 5400 to 6400 (plus the extra 2" pitch on the prop) and the boat now gets up on plane (or as close to that as a toon can get). The ride's better and the boat handles better. Trim is now a big deal. Too much bow down and it mushes and you have to fight the torque. Too much bow up, and it gets really sensitive on the steering. But in the sweet spot, it handles like a dream. Also the 90 is much quieter than the 60 - go figure!! I nearly opted for the 115, but all the experts advised against it unless I got hydraulic steering (for an additional $2 grand). Thanks to all who offered opinions and advice. So long for the moment.

is that 6400 rpm's a little high? not sure but thought max for 4 strokes are 6000?

Coplas01 said:

Getting about 5400 rpm WOT. Prop has a number stamped on the side that's difficult to read, but I believe it ends in
11p15. I presume that's pitch & diameter. Am I right with my information that a "Big Foot" on a 60 is the same lower unit, gear ratio, prop, etc that's on the 90's and 115's? The boat I test drove had the same pontoon tubes as mine, but a different seating configuration and a foot longer deck. I saw it on a trailer and didn't notice any lift strakes. On the boat packages from Sun Tracker that offer 90's and 115's as optional motors, the 115 is $1000 more than the 90. I don't see any way that can include hydraulic steering.

Click to expand...

If you are indeed running 11p15 then your boat is propped wrong. I have the same 2011 party barge 20 with a 60hp mercury bigfoot. My boat has a mercury prop designed for the bigfoot. Mine is a 14p11 and I have seen 21mph(gps) at 5400 rpm. I lose 1mph for every 100 rpm down to 3300 rpm or so. Most of the time (wet and loaded with my wife and I and gear) I see about 5200rpm at WOT. I like to pull a tube and the motor bogs and won't maintain rpm very well when turning, so I was thinking of going down 1 in pitch to a 14p10 to increase my torque and get my rpms up at WOT when pulling a tube. Lowest rpm I've had while towing a tube in a straight line in rough water was 4800. I'd estimate that would be about 17mph. I had 3 "FULL GROWN" *****s on the boat and 1 on the tube.

Sun Tracker website lists the top speed difference between the 60hp bigfoot and the 90hp mercury as 3mph. Not saying you didn't gain what you said, I'm just thinking that this further supports your 60hp bigfoot was propped wrong. I also agree that 6400 seems high. You might want to consult your owners manual to find if 6400 is in the WOT rpm operating range for that motor. You might be under propped if it is higher than the manual states.

Thanks for the responses, folks. Bass Tracker lists the top rpm for the 90 as 6000. I'll check around and see if I can find some recommendations for propping it properly. Had 3 big people and 3 children on the boat the other day, and it pulled a tube with an additonal big person and 1 child at just under 6000 rpm. That was with a full 30 gallon gas tank, 2 batteries (1 for trolling motor), and all the other associated stuff we keep on the boat. We live on a small lake, so I don't run WOT except when we're tubing, so perhaps it's propped correctly for the way we use the boat. In retrospect, I should have examined different propping options for the 60, but I was so frustrated with the dealer that I just wanted to either be rid of the boat or the problem. I don't have a trailer, so all folks who service boats and motors charge significant trip charges just to come out. At least now, I'm happy with the boat. It rides considerably smoother, presumably because the additional speed causes it to ride higher in the water, and the performance while tubing is what I'd hoped it to be.
Again - thanks for all the good advice.

Are you looking to sell the MERCURY 60hp. BIGFOOT?
let me know if you are.
[email protected]
thanks!