Help boat is not as good as it was

[Ghost Rider 2]

I am looking for some help in trying to get my boat back into the balance it was before. I have a 1972 Winner Wildcat. 18' closed bow. This boat is pretty lite and handles great. The problem is, I had a 135hp Chrysler outboard on the boat. This is the outboard that came with the boat new. The end of last season I lost a cylinder. The Chrysler was a 4 cylinder. I replaced the outboard with a 140hp Mercury. inline 6 cylinder. I know that the outboard is heavier than the Chrysler. The Chrysler would run about 5200 full throttle 42 mph 1 person 36 mph with 3 to 4 people. It had tons of power and would pull multiple skiers. The Mercury will run up to 5500 full throttle. Will run over 50 mph with 1 person and 45 with 2 to 3 people. Boat has trouble pulling skiers seams to labor at a low rpm. Also I am getting a ton of water spray behind the boat. And the boat tries to porpus at anything under 4750 rpm. Planes fine and runs greaty a high rpm, but will not cruise smooth at lower speed. Will a stingray fin help? Wife is not happy with the boat anymore, and I am not ready to trade. Sorry about the long post but I am trying to give all the information I can.

 

[NW Redneck]

Re: Help boat is not as good as it was

Sounds like the heavier engine has changed the balance point. I was considering a stingray for my boat, but after a little research and some searches here on iboats I've decided the smart-tabs are the way to go. Should help with the porpoising and get you on plane faster.

As far as pulling skiiers, you may need to change props. Check and see what diam/pitch your current prop is and try posting a thread in the prop forum. Some smart cookies in there that might be able to help you.

 

[tashasdaddy]

Re: Help boat is not as good as it was

check your engine height compared to the bottom. AV plate should be even and in line with the bottom or above.

 

[studlymandingo]

Re: Help boat is not as good as it was

I agree with both of the above posts, could be a difference in props, or weight distribution. Hydrofoil is not the answer, that would most likely cause more problems. The smart tabs are a great addition, and would most likely greatly help your woes. Also, "venting" your prop may help with the holeshot. Do a search in the prop section on venting.

 

[Texasmark]

Re: Help boat is not as good as it was

Not discounting what others have recommended, but what you are telling me is that your pitch is too high on your prop for anything more than joyriding alone, and that it's higher than the Chrysler (taking gear ratio into account if different) was.

I never used tabs so I can't comment on them. I know how they work and why, and that they help to get the bow down which helps you get out of the hole, but with a skiier, you need more tugging power coming out of the hole.

I have however, used lots of props and when I prop out for high speed (which is what you are doing with your 50 mph) I cannot get the hole shot. Sounds like your setup is perfect for 1 person.....rpms right on and speed great.

Notice that you dropped 8 mph alone and 9 mph with 2 aboard with essentially the same hp. Also note that you were able to pop skiis up and now you can't.

I have never been able to pull waterskiis with a prop that met my high speed expectations. Reason why is that you have the engine loaded for the high speed run.

Once you increase the weight in the boat, or try to pull up skiis, you are overloading your engine so somewhere you have to reduce the load on it. One way is to reduce the pitch, but in your case if you reduce the pitch with another prop, you will be under propped for your joyriding alone, so something else has to happen.

One thing that unloads the engine in trying to get a skiier up is a prop with ports in it. The ports are holes in the side of the prop and allow exhaust gasses to blow across the blade which deliberately causes the prop to ventilate.

This ventilation unloads the engine and it responds by running the rpm's up reasonably high, reasonably fast which allows it to quickly develop it's hp and put it to use; no lugging.

As the rig gets under way, water pressure caused by water flowing past the hub, and the vacuum caused at the rear of the hub will seal off the holes and you don't know they are there; top end is unaffected.

Walleyehed, on props forum has been talking about the new Merc Enertia Prop (Spelling is correct) which is said to be capable of solving the hole and high speed problems simultaneously. Might give it some thought.

Personally, the cheapest and maybe the best fix for you is to take your prop to a reputable prop shop and have them port it for you.

HTH

Mark

 

[Chris1956]

Re: Help boat is not as good as it was

Ghost, The Merc engine should be a vast improvement over the Chrysler. You should look up both on the NADA, and compare weight. The Merc is 300#, and depending on the year makes from 130-140 HP at the prop, which is likely significantly more than the Chrysler. It is also likely lighter in weight, and will have much greater midrange pull. d

It does sound like you have too much pitch on your prop. Also, if that motor doesn't have PTT, the tilt pin should be in the second hole from the bottom, to start. If you get porpoising at that point, something else may be wrong. You will need to experiment to get the correct prop, however you might like to start with a two inch lower pitch prop and adjust up or down depending on WOT RPM.d

You may also like to verify that your tach is correct.

 

[JasonJ]

Re: Help boat is not as good as it was

Also, Inline 6 Mercs should be propped so they arenear 6000 rpms with one person and a light load. they love to spin, and they can spin higher than 6 grand, but that is best left to the racers. I would definately kick your pitch down to the lext level. Also, power tilt & trim was not mentioned. If you do not have power tilt & trim, you will have to do a lot of tweeking. I run mine 4 holes out, and that gets me around 5900 rpms under light load.

You might have to run two props. Low pitch for ski day, and high pitch for quality alone time. It takes minutes to change a prop...

And yes, a Merc inline 6 is very light compared to other manufacturers, and Mercs need to rev. Good luck....

 

[Texasmark]

Re: Help boat is not as good as it was

My Merc was. 85 Chry vs 115 Merc. .5 on fuel 2x on speed. Never have a Chry again.....but I do have 2 Dodge P/u's......no relation and a Merc; a relation. And if I don't die B4 I wear them out will buy another P/U and Merc. 8)

Mark

 

[Ghost Rider 2]

Re: Help boat is not as good as it was

Thanks for the imput. I will pull the prop and get numbers from it. I will post size over the weekend. I hope that a prop change will help this boat out.
Also the boat does have power tilt and trim. I have to keep the engine down some. If I trim it all the way up, it will porpuss terrible..

 

[Ghost Rider 2]

Re: Help boat is not as good as it was

Just went out and pulled the prop. It looks like the # is 052093. I could not find anything on that #. So I am going to presume that the # is accually 032093. It is a litte scared up at the #. If the 032093 is correct. I find that it would be 13X19. How far off am I?

 

[Ghost Rider 2]

Re: Help boat is not as good as it was

I have not changed the prop yet. But I did take the boat back out and tried a hydrofoil. It did help the boat a little. Does not porpuss as bad. I can get the boat pretty smooth as low as 4200 rpm. But I still have a ton of water spray at the rear. If I trim the motor in very deep it will pump up the transom and come in the back of the well. Looking for a prop to try. Also am thinking of adding a hundred or so pounds of balast wieght in the bow.

 

[Texasmark]

Re: Help boat is not as good as it was

Unless you have something like a speedometer sending unit or depth finder transducer handing off the transom and making your rooster, it sounds like your engine may not be at the right height. Dhadley or Walleyehed know about that. Also, you can cure porposing by going above it (in speed), below it, or trimming in till it stops. My Merc has 2 plates to deflect it so the engine mfgr knows about it. Possibly your lower one is below the bottom of the boat meaning water is passing over it, rather than under it, and rendering it useless....from an anti-spray standpoint.

Mark

 

[hiflyer]

Re: Help boat is not as good as it was

try a 17" pich. a good dealer will lend it to you to thy it out.
should up the top rpm 250-300 light load and possiable lower the rooster some

 

[Jdeagro]

Re: Help boat is not as good as it was

Check the engine height as recommended. You should not have spray comming off the back unless something is dragging in the water that should not be.

The Hydrofoil will help some on the Hole shot but may give you other handling issues. The porpoising is a balance problem which you should not attempt to fix by adding additonal weight as this will simply cost you more fuel consumption and likely handling issues.

Work on one thing at a time.

 

[Ghost Rider 2]

Re: Help boat is not as good as it was

I have looked at the hieght issue. This Mercury sits within a 1/4" of where my Chrysler sit. Measuring from tramsom top to plate. Merc is the shorter one. The Winner boat does have a hull design that drops to a point at the bottom. The boat sits in the water different than it did. I would say that the Mercury would weight in at 100 plus pounds heavier. I have noticed that the boat improves as the fuel load burns down. I have a Clymer shop manuel that shows a Wellcraft with a merc on the cover. My engine is running in the water at the same hieght as it is , but my turbulance behind the boat is many times worse. Should I try to raise, or lower the engine? I am very confussed on what I should do with this boat.

 

[hiflyer]

Re: Help boat is not as good as it was

try down a little, if its easie. do not start drilling new mount holes

 

[studlymandingo]

Re: Help boat is not as good as it was

Your A/V plate should be just about even with the pad at the bottom of the boat. What Winner model do you have? I have the 1850 CC, and it steps in a bit at the bottom, my A/V is just about even with the bottom of the boat, I don't have a rooster tail. Is the hydrofoil out of the water when you are running on plane?