25hp mercury outboard nedd more performance!!!

[imported_BEN]

Hey guys i currently have a 25 hp mercury 4-stroke outboard i think its like a 2003 model. Its EFI and is completly stock. I need something to help give me more speed. My boat currently barely plans off. I was thinking my a hydrofoil?? do they really work? Or a better prop? but what pitch? or any other kind of upgrade yall can think of let me know. Thanks ben

 

[narvlebenoit]

Re: 25hp mercury outboard nedd more performance!!!

Ben. what size boat do you have the motor on.maybe you need a smaller boat

 

[imported_BEN]

Re: 25hp mercury outboard nedd more performance!!!

Well yea that would obviously help but it is one a 16 foot fisher. The reason i have a 25hp is because of the lake i fish has a 25hp maximum. I am just looking for a little more power. When its just me in it it runs fine. But when you put someone else and some gear it struggles.

 

[Expidia]

Re: 25hp mercury outboard nedd more performance!!!

Couple of things to try . . . I don't know what gear you have but I used to keep my transom trolling motor battery on a long cable and stored it up front when I had to deal with a former under powered rig.

Same for a plastic gas tank.

Hard to say without seeing a pic of your boat. Take a pic from the side too with the o/b in it's vertical position. That will help us assess if your cavitation plate is in the correct position.

I bought my current rig new from a dealer and they had the outboard mounted two hole to low. Which caused undue drag in the water. They don't test drive it. They just want it out the door once it's delivered.

I would first look to tweak the height of the cavitation plate to tune the O/B to your model boat.

And then look to balance the gear. There is not much you can do if the boat is underpowered. A hydrofoil would help, but make sure the height of the O/B is correct before you go at your O/B with a drill to put 4 holes in the cav plate.

And find some thinner girlfriends . . . .

There is always the buy a higher HP outboard and buy the lower HP rating stickers off Ebay, but you didn't hear me say that. Of course, as long as the new o/b is below the maximum on your boats spec plate. I'm not advocating this, just pointing out that some people will do this to get around lake hp minimums. You could be sued big time if you got in a boating accident and falsified the HP rating on your o/b.

 

[will941s]

Re: 25hp mercury outboard nedd more performance!!!

The 25 you have should push a 16' boat pretty well. Looks like you need to have the problem figured out, like it was mentioned in the previous post, the plate should be even with the bottem of the boat, not above or below it. If the boat is heavier, go with a little less pitch prop, get those RPM's up. Maybe some gear relocation would help. I have a composite adjustable prop that I can change the pitch instead of having 2 or three props on the boat. When I go out alone, I run 13 pitch. When I have people with me and extra gear I go to 12 or 11. If you try it and it works, you can pick up some extra planing performance with a hydrofoil. Help you get on the top of water a little quicker, and help you stay there.

 

[imported_BEN]

Re: 25hp mercury outboard nedd more performance!!!

Yea i have relocated my batteries and it helped some as far as where the motor is mounted im not sure where the right spot is? maybe you could tell me what to measure or what hole it should be in? I have considered boring it out but before i went through the hassle and expense of that i was trying to see if there is a cheaper and easier alternative. I imagine a new prop with a different pitch would help but im not real sure what pitch to go with

 

[Moody Blue]

Re: 25hp mercury outboard nedd more performance!!!

Not totally above board but you could buy a 40hp motor then switch out the cowling from the 25hp . Is this an alum fishing boat?

Pretty hard to correct an underpowered problem. Hydrofoils won't give you any more hp but MAY help get you on plane quicker. They MAY also really screw up the handling. Better option would be to install smart tabs. Highly rated on these forums and I've used them with great success.

What is the pitch of the prop you are running now? Assuming the prop you have now is the right one to achieve the proper max RPM, then changing it would result in the following....

.... lower pitch improves hole shot (faster to plane), reduces top speed, increases RPM (careful not to exceed max RPM)

.... higher pitch degrades hole shot (slower to plane), increases top speed, decreases RPM (careful not to lug motor)

With you current setup, have you tried adjusting the trim angle of the motor? Where is the anti-ventilation plate relative to the bottom of the boat?

 

[Expidia]

Re: 25hp mercury outboard nedd more performance!!!

Props are a pain to keep on swapping on and off. I have two one OEM and another of a different pitch for more people on board but I have it for more for a spare to keep on board.

What is the max O/B for your rig?
This way you can better assess how much you are under powered and what steps you can do to get a little more oomph out of the 25 hp.

Since my rig has the max HP O/B it does not matter what prop I have because it pops on plane in two feet. Since you don't have that luxury you need to first get the O/B in the proper holes before you spend money on props that might not help your issue.

Take a close picture from the side of the cav plate and where it aligns with the bottom of the transom and get back to us.

 

[imported_BEN]

Re: 25hp mercury outboard nedd more performance!!!

I have coinsidered the smart tabs i just cant find one for a 16 foot with a 25hp motor. They have one for a 16 ft for a 40hp which would probably work.

 

[imported_BEN]

Re: 25hp mercury outboard nedd more performance!!!

ok i will take a picture tomorrow morning i am at work today so i wont be able to.Also i think thew max for my boat is a 60 or 90 but i will find that out tomorrow as well. i will also find the pitch of my current prop. thanks for the help guys

 

[Expidia]

Re: 25hp mercury outboard nedd more performance!!!

This company seems to list them. I didn't think they made them for 16 foot or less boats. When I was contemplating smart tabs for a smaller rig I had , no one offered them.

http://www.nauticusinc.com/smart_tabs.htm

A lot more expensive then raising or lowering the o/b 1 hole though if that's that might be needed.

And smart tabs may not help if the O/B is dragging too low anyway.

 

[Expidia]

Re: 25hp mercury outboard nedd more performance!!!

ok i will take a picture tomorrow morning i am at work today so i wont be able to.Also i think thew max for my boat is a 60 or 90 but i will find that out tomorrow as well. i will also find the pitch of my current prop. thanks for the help guys

If it's 60 or 90 . . . probably most things you try won't do much do to the design of the hull, the manufacturer has put the rating pretty high. It's probably closer to 60 hp, my guess would be 50 hp. unless it's fiberglass then maybe 60 hp. Just look up the specs on the web for your model and year.

Mine is a 15 foot aluminum and the max hp is only at 40 hp.

 

[imported_BEN]

Re: 25hp mercury outboard nedd more performance!!!

here is a link to my boat. Although it is a 2003 model same boat. The max hp is a 75.

http://www.fisherboats.com/boat/specs.cfm?boat=2983

 

[Expidia]

Re: 25hp mercury outboard nedd more performance!!!

here is a link to my boat. Although it is a 2003 model same boat. The max hp is a 75.

http://www.fisherboats.com/boat/specs.cfm?boat=2983

Well there you go . . . That's one part of the equation. And it's not good news because you are expecting to move over 1000 lbs of boat with gear and get it to plane yet the max is a 75 hp.

If yours has those floors and lockers, that's a lot of boat to get quickly on plane with a 25 hp.

As another poster said already said, from here you need to tweak the 25 hp for maximum performance, it's going to be a process of elimination of the other variables.

You can start with the pic of the cav plate location tomorrow!

If foils or wings work so great, why don't the manufactuers offer them? They put strain on the lower end and can make the handling in turns dangerous. Probably won't help all that much, but it's always a last resort.

I know what you are going through trying to make an under powered rig get on plane. I struggled with 2 other rigs doing just that.

When I bought my 07 the dealer sold me a new 06 Merc 30 hp leftover he had. He assured me up and down that this hp will get me right up on plane even with 3-4 people on board.
I had to walk out onto the bow while at full throttle and it still took the length of a football field to get it up on plane. Then of course, another boat would cut in front of me and I had slow down and do it all over again.

Don't ever believe the line of BS from a boat dealers, used boat dealers, car salesman, the previous boat owners story of why they are selling such a great boat etc . . . hahahaha

So two weeks later I gave him his 30 hp back and ordered the 40 hp for only $500 more which included the installation swap. The 40 is the max for my rig. He said it must have been a linkage problem.

Come to find out the reason he was dumping the 30 on me was because the 2007 40 Merc EFI ELPT was about 40 lbs lighter than the same 2006 30 hp model. Boat pops on plane now in 2 feet. Any wonder why this dealership changed hands last year!

 

[Moody Blue]

Re: 25hp mercury outboard nedd more performance!!!

Based on the boat/motor you have, I'd say you are flogging a dead horse. If you are underpowered by 50HP, there is not much you can do that will make any real difference. I see three options.

1) get a bigger motor
2) get a smaller boat
3) live with what you have