Another Speed Question

[plane jim]

Hello Skippers-I own a 21 foot Sun Tracker Fishing Barge, It is powered with a two-stroke 60HP Mercury . My big question-My speedo is way wrong according to my Handheld I-phone GPS. Speedo reads 26 mph and the GPS states 20.3 mph. I have a feeling that the GPS is right but I would like more top end.

The boat is rated up to a 90 and I found a smoking deal on a 115-what would be the problems and or advantages of sticking a 115hp on this toon-thanks in advance for any thoughts!!!!!!!!

[Redneck_Randy]

Over powering a boat with a bigger motor other then it's approved for can cause you insurance problem. Also read stories about boats being over powered and the lake patrol impounded them.

[evinrude2stroke]

+1. I don't think that's a good idea. You have to factor in weight. It will probably be too heavy for the boat. LE could yank it if they board you and see that it's over the limit. Also it would definitely be an Insurance issue if you had a bad day.

[plane jim]

I also forgot the mention that the 60 Bigfoot that is presently on the boat in rated for 5500 rpm although I have only got 5200 rpm at best with full fuel and alone in the boat-thanks

[Redneck_Randy]

I also forgot the mention that the 60 Bigfoot that is presently on the boat in rated for 5500 rpm although I have only got 5200 rpm at best with full fuel and alone in the boat-thanks

You don't have the right pitch on the prop. Go to a Mercury dealer and they will help with the right prop for your pontoon.

[plane jim]

The mercury dealer here sold the prop and motor to me-they stated the rpm is right on the money for the application-as I stated earlier the tach shows 5200 and the motor is rated for 5500 max-would 300 rpm make a real speed difference? It reaches 20 mph really quick but I would desire more speed-thanks

[Redneck_Randy]

would 300 rpm make a real speed difference?

No

[plane jim]

thanks for the reply-I think I am going to put a larger motor on this one

[screwball]

The Merc 60, 75, 90, and 115 are the same motor. Bore and stroke are the same, weight is the same. You will run into insurance problems IF CAUGHT. If you put that 115 on there, go to your local Merc dealer, or go online and order the 90hp graphics, or just take off the 115 on the rear of the engine. I'd do it in an instant if I found a deal on a 115 and my transom is only rated for a 75.

[rancherlee]

Being over 20' long (and not a mono hull) it's not against Federal law to over power the boat, and the majority of states have laws based around that so check local laws. As far as insurance goes It's not too hard to get a policy writen and be covered as long as you give them the facts and tell them what size outboard is on the pontoon. That said a 115 is going to only give you 1-2mph more over a 90 on a pontoon. Going from a 60 to 115 will give you 6-7mph and double your fuel usage @ WOT, is it worth it?

[NH Tooner]

Lower the pitch on the prop by 2. It will not give you more speed but put you inthe right range for cruising and everything else. Go with the 115. I would.

[gramps]

The mercury dealer here sold the prop and motor to me-they stated the rpm is right on the money for the application-as I stated earlier the tach shows 5200 and the motor is rated for 5500 max-would 300 rpm make a real speed difference? It reaches 20 mph really quick but I would desire more speed-thanks

I think you are at the correct speed with your set-up. The rpm's are in the correct range, don't waste your money for 300 rpm's and it won't guarantee any more speed.

[GregF]

The Merc 60, 75, 90, and 115 are the same motor. Bore and stroke are the same, weight is the same. You will run into insurance problems IF CAUGHT. If you put that 115 on there, go to your local Merc dealer, or go online and order the 90hp graphics, or just take off the 115 on the rear of the engine. I'd do it in an instant if I found a deal on a 115 and my transom is only rated for a 75.

75 and 115 are the same, 60 is almost 100 pounds lighter.

[GrandpaGreg]

The Merc 60, 75, 90, and 115 are the same motor. Bore and stroke are the same, weight is the same. You will run into insurance problems IF CAUGHT. If you put that 115 on there, go to your local Merc dealer, or go online and order the 90hp graphics, or just take off the 115 on the rear of the engine. I'd do it in an instant if I found a deal on a 115 and my transom is only rated for a 75.

75 and 115 are the same, 60 is almost 100 pounds lighter.

Actually the 40, 50 and 60 are the same

[GregF]

The Merc 60, 75, 90, and 115 are the same motor. Bore and stroke are the same, weight is the same. You will run into insurance problems IF CAUGHT. If you put that 115 on there, go to your local Merc dealer, or go online and order the 90hp graphics, or just take off the 115 on the rear of the engine. I'd do it in an instant if I found a deal on a 115 and my transom is only rated for a 75.

75 and 115 are the same, 60 is almost 100 pounds lighter.

Actually the 40, 50 and 60 are the same

Exactly and so is a Yamaha F70, hence why I have one.

If you want to be pedantic about it the merc 40 non big foot is smaller.