Sluggish when planning out (help please!)

[MallardC130]

I have a 1978 Merc outboard fitted on a Mark Twain tri hull. I am experiencing loss of power when trying to pull a skiier or just planning. It almost sounds like the prop is running in air from 5mph to 15mph. Then the power comes back. It takes awhile to get to 20mph and cruises at 30 mph.<br /><br />I have a new prop on and the hull is good.<br /><br />Second problem is that when starting out the boat veers HARD to the right until higher speeds. Any suggestions????

 

[sundog]

Re: Sluggish when planning out (help please!)

what size of your engine, size of the boat, and pitch on the prop? right off Id say check your engine height on the tansom. ventilation plate should be right at the bottom of the keel, within an inch or so. <br /><br />that said, I was just about to post a thread about my 1978 1150 on my 1964 evinrude tri hull doing pretty much the same thing (I have a 13x17 pitch prop, and my vent plate is right where its supposed to be). if I slam it down, prop will ventillate (works OK with nice smooth acceleration), and anything other than a gentle turn at speed will cause the prop to ventilate. had the prop cupped, and that helped some, but still ventilates in turns. Would a 13x19 prop make a difference (boat is slightly overpowered, Im sure the engine can handle the prop). Ive never had a tri-hull before, and never had this problem. maybe the outer sponsons wont let the boat heel in a turn causing more of a skidding turn, which could move water over the prop differently? Im clueless on this one.

 

[quantumman29]

Re: Sluggish when planning out (help please!)

first of all, is the boat equipted with a power trim? ( this is the unit which raises and lowers the engine by the use of a button on the gear shifter or the steering wheel)?<br /><br />if you do have a power trim system, lower the engine all the way down(tucked in) and then slooooooowly begin to accelerate,as the bow of the boat begins to slowly rise,you should be throttling the engine up and raising the engine at the same time( do not raise the engine too much to soon)as the bow begins to level off and continue accelerating until the trim and engine have reached the optimum cruising height(this will vary between different sized and weight boats,trial and error is the best way to determine and know the proper position and the comfort zone for your boat and its trim location.<br /><br />as for the steering problem,this too may be due to improper engine trimming , once you get used to blasting off and attaining the proper trim for cruising,you will become adjusted to it and it will all be second nature....<br /><br /> mike

 

[quantumman29]

Re: Sluggish when planning out (help please!)

one more thing, you can get a set of whale fins for the lower unit ,they are quite easy to install and they help a great deal getting the boat up on plane easily..... <br /><br /> mike

 

[jimmbo]

Re: Sluggish when planning out (help please!)

Sundog<br />You have Evinrude Sweet 16 or a Sport 16? that boat had a HP rating of 130 or 140. here's a link for you<br /><br /> http://www.ultimate.com/omc-boats/

 

[MallardC130]

Re: Sluggish when planning out (help please!)

Thanks for posting to my problem! <br /><br />The engine is a 115hp Merc. I have a 15 prop on it now. I do have trim and have been using it to get better performance out of the engine but it is insanely slow to get it to plane out and the prop sounds like it is ventilating.<br /><br />What is a transom? Will cupping the prop help? Does a whale tail really help? ( I always thought they were just a gimmic.) What exactly causes the boat to want to pull to the right when I try to pull a skier out? I took it to the shop to get the skeg welded on after it was knocked off and the mechanic said it was the best 25 year old engine he ever ran. So I dont think it is a engine problem but more of a prop, engine placement problem. Any suggestions?

 

[quantumman29]

Re: Sluggish when planning out (help please!)

dude?<br />learn how to get the boat up on plane smoothly before attempting to pull skiers,learn how to adjust the trim and accelerate or decellerate(is that a word) it sounds to me that your over accelerating while the engine is tucked in too much thus pulling the boat to the right,<br /><br />to smoothly get the boat on plane you need to slooooooowly accelerate and raise the trim(engine) at the same time as your accelerating,this dosent require high speeds,it just requires alot of practice and getting to know the feel of your craft....<br /><br />it is almost impossible for anyone to learn about proper planning by reading,all boats will and do handle differently,you need to practice,<br />it sounds like the only problem is your not getting used to the trimming of the engine..<br /><br />the TRANSOM is the back of the boat where the motor hangs off.......<br /><br />whale fins are no gimmick! they absolutely help the boat get on and off plane alot!<br /><br /> mike

 

[sundog]

Re: Sluggish when planning out (help please!)

Jimmbo~ I have the sport 16. Ive been to that site many times researching the boat. It seems the inboards are rated for 130-155hp, but the outboards I couldnt find much legible liturature on. under OMC liturature, down where it says "Jeff Castons 1964 lit", click on the 'family room pic', and you can barely read the 2nd para, where it looks like its rated for 40-90hp. Its a very light boat, big surfboard, really, 115hp is more than enough.<br /><br />took the boat out again today. its still ventilateing pretty badly in turns (so much so that my wife wont drive it). Im going to try a 19 prop, then if that dosnt work, lower the engine another inch (gotta cut the damn transom I just installed in it to do that. grrr!)

 

[LubeDude]

Re: Sluggish when planning out (help please!)

Waite, waite, waite, You are just not giving us enough information to help you out. <br /><br />What kind of prop, aluminum or s/s?<br /><br />Cupped or not?<br /><br />Where is you cavitaion plate in relation to your bottom?<br /><br />RPMs at WOT?<br /><br />Are you trimmed back down when turning? You should be.<br /><br />Fill us in better.