I have 115 merc efi 4 stroke on back of a sea pro 186. I know its a bit underpowered and has always taken a bit to get on plain but I feel like it takes too long yesterday like something has changed. once it’s plained it runs great.
Any ideas?
Water in the hull, too much weight near transom, bent prop blade, wrong trim pitch at take off, etc?
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Can’t help with the underlying problem as it is difficult to diagnose online, but if you don’t already have a stabilizer fin/Hydrofoil on the motor, they do work… Had the same problem years ago, and the fin fixed it for the most part…
thanks guys. i’m headed out today to try a few things.
If nothing visible has changed then water in the hull is a good possibility.
Also growth on the hull can happen within 72 hours in warm few water. Even a little growth will slow you down.
took it out yesterday just me and wife and it was “normal”. I think i’m simply underpowered and will probably go with what RBF said. Another guy at the boat dealer told me same thing.
Try re-propping. Maybe go to a four blade. If those gadgets, really, worked you’d have had one on it from the get go, from the Dealer. After all of the engineering that goes into the manufacturing throughout the Marine Outboard Industry, you think the major players would let a gimmick be the solution to their problems? Bet you can’t find on a with a major manufacturers brand on it?
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Anyway, good luck…
I believe hydrofoils work, but perhaps not in every situation… They only cost about $50 and are easy to install… It made a lot of difference for my situation…
The problem with NMMA standards for outboard HP nameplate ratings is they allow for +/-10% HP variance… Hence your 115HP could be only putting out 105HP… Boat dealers will also outfit with lower HP motors just to be able to lower the overall cost of buying the boat when new… Couple these 2, and someone could really be underpowered…
Nothing to stop trying both options… Try either re-propping, or a hydrofoil, and if it doesn’t work adequately, add the other… Perhaps both are needed to do it if it is seriously underpowered…
The whales tail type is not recommended for evinrude / Johnson type engines and some others. I have seen them break the cavitation plates completely off. And while the foil makers offer a warranty , it is very limited. Check with the engine manufacturer before you drill holes in the cavitation plates
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Good point… Some of the “whales tail” types are made of aluminum which would prolly make it more rigid which may result in breakage… I had the “Stingray” type and it was made of heavy duty plastic… It would be better to have a hydrofoil that would break/flex before the motor fins… Anyhoo here’s what I bought and it was many years ago…
I’ll reply to your comment in the Off Topic here, RBF. No “Bearing Buddy’s” for me. They’re just another failed gimmick, lulling unsuspecting people into assuming their bearings are properly lubricated. Sorry, but that’s the truth!
Bearing buddies can work if you remove the grease seal and reinstall it backwards allowing grease to “purge” through both bearings and out the back. the seals lip is designed to keep grease in hence the bearing buddies only provide a little grease to the out side of the outer bearing and never get to the inner bearing. Best over all grease system is a spindle that has a drilled hole all the way past the outer bearing and forces grease through both bearings and purges out the front, keeping the grease seal as it is intended.
Hammurred, On your boat, what’s your top end RPM’s? They are harder to find but you can order an even number pitch. Each inch is worth about 300rpms Lot’s of discussion about it, but a Yamaha will stand 6000-6200 rpm’s no problem all day long. I don’t have a selection any more to let you borrow, but you would be amazed by different manufactures, designs, and pitches on props and how they preform. I’ve even seen two “identical” props preform different. Find a buddy with a prop to borrow before spending a bunch on purchasing one if you can. Another option is to take it to Skip’s prop shop and have him do a little work to your prop. Just tell him what you’re after.
With the prop and everything the same ,did the boat ever drive out correctly?
yea, if I don’t have anyone sitting in back when I hit the throttle, it comes up OK. Not as quick as my old boat, but it’s not a huge deal. amazing what a few hundred extra lb’s in the back will do. I thought something was wrong with the engine like compression or gas.
Sounds like to me its the OE
Its almost always the OE on those boats.
Thats my guess anyway
I would definitely do a compression test. Compression is power. !