**1988 Scorpion Eliminator Set Up**

[scorpion300x]

The Scorpion has gone thru some changes New Motor 2005 300 x having a porpoising problem. Before I had a 225 special edtion Johnson which I blew the motor last year. Have a Hyd jack plate and 14 inches of set back at that time the only problem at high speed around 75 miles and hour it would crab go left to right side to side and i have remember correctly it might have been below the pad a little at that time.

The 300 x I had raised the motor 2 notches with the hydr jack plate and have a porpoise problem at about 80 and have to back off on the speed I lower the jack and lose rpm and can seem to get the boat at 90.

I had tried 28p 3 blade cleaver it ran terrible picked up the stern to much made it squrrely also a 3 blade chopper 28 has a tendency to porpoise more at 80, 4 blade 32 p spinelli ran better but still that dam porpoising.

I have jacked motor down but loose rpms and trimming the motor up and catch to much air lifts the nose to high.

I need help




Steve

[scorpion300x]

Come on people need some help

[Liqui-Fly]

Steve how high are you running the motor now with regard to propshaft and pad? Keep an eye on water pressure and run it up.

[ChrisXS2003]

If the boat didn't porpoise with the 225, the first thing I would suspect is that the additional weight of the big 300 is the culprit. Porpoise is usually due to a lack of lift. The boat is trying to lift and it can't because of weight, power, balance, prop, etc.

If it were mine, I would try as many props as I could get my hands on. If it can't be tuned out with props, the last resort is to reduce setback. I know, that's a P_I_T_A$$!

You may learn something in the prop trials though and that could help figure out what it's doing, too.

Someone who really knows that hull could help, too. I think Ron Baker Sr. is intimate with that hull. He's in Florida now, but I'm sure he could help.

Chris

[scorpion300x]

Anybody know of Ron baker sr. in Florida need to talk to him about my Scorpion

[scorpion300x]

Steve how high are you running the motor now with regard to propshaft and pad? Keep an eye on water pressure and run it up.

Hi Liqui-Fly
A little above the pad maybe thats the key, I am told on these boats that they run better below the pad a little

[300x Stoker]

When he took the Johnson off and put the 300 on he reduced his set back but I can't tell you how much. Last I heard he was at 95 without any problems. Have you tried trimming up a little till you get through the hop zone, then trimming down??

[scorpion300x]

When he took the Johnson off and put the 300 on he reduced his set back but I can't tell you how much. Last I heard he was at 95 without any problems. Have you tried trimming up a little till you get through the hop zone, then trimming down??

No I havent tried that but ill give it a shot as far as reducing set back I would think you would need more set back but im no expert.

I wonder who that guy is that you are talking about 300x stocker, does he have post on here?

I took the boat out last Wensday and brought the boat just above an inch above the pad and trimmed the motor up a good fair amount and trying to get it over that hump to stop the porpoising problem , just cant seem to get there yet. I did get to 90 though one time I just rode it out while it was porpoising scary but had to try somthing new.

Any poeple know of any one who has a Eliminator Scorpion 20" tunnel hull let me know or the same problem with this type of hull please chime in

thanks

Steve

[ChrisXS2003]

IMHO, the porpoise is from the hull trying to lift the tail to release the air entering the tunnels and then falling back down. It's trying to swallow a big gulp air (KK's analogy). By reducing the setback, you'll be moving the CG forward and allowing the tail to lift easier. Also, when you trim it up to pack the tunnels, the bow will be less likely to overreact.

The chopper is a bow lifter. It's trying to lift the bow, but it wants to clamp down the tail to do so. Also recognize that when the bow goes up, the tail goes down and it wants to dig in the prop (especially with that much setback). That's why the propoise was more pronounced with the chopper. The 4 blade has good overall lift, helping lift the tail while still carrying the bow. That's why it ran better.

If it were mine, I would focus on trying props, although it's still just a bandaid. I wouldn't think the boat could reach it's ultimate potential with prop changes alone

Just my 2

Chris

[Massbasser]

What is the weight of the 225 OMC? The 300X is 480 pounds, I doubt there was much difference in weight between the two motors, go back to the setback you had before.

[scorpion300x]

IMHO, the porpoise is from the hull trying to lift the tail to release the air entering the tunnels and then falling back down. It's trying to swallow a big gulp air (KK's analogy). By reducing the setback, you'll be moving the CG forward and allowing the tail to lift easier. Also, when you trim it up to pack the tunnels, the bow will be less likely to overreact.

The chopper is a bow lifter. It's trying to lift the bow, but it wants to clamp down the tail to do so. Also recognize that when the bow goes up, the tail goes down and it wants to dig in the prop (especially with that much setback). That's why the propoise was more pronounced with the chopper. The 4 blade has good overall lift, helping lift the tail while still carrying the bow. That's why it ran better.

If it were mine, I would focus on trying props, although it's still just a bandaid. I wouldn't think the boat could reach it's ultimate potential with prop changes alone

Just my 2

Chris

Hi Chris ,

Thanks for the input and help , I just got off the phone with Ron Baker he built these boats , back in 88 an said the same thing your are saying. They ran the Johnsons with no set back. Thats going to be the key to my success.
He was saying you really have to trim it up high to pack that air under the stern. I should be using 3 blade choppers and have it really cupped to carry the bow.

If anybody whats to chime please do and anyone that has owned a 87-88 Scorpion Eliminator please reply back

once again Chris thanks

[scorpion300x]

What is the weight of the 225 OMC? The 300X is 480 pounds, I doubt there was much difference in weight between the two motors, go back to the setback you had before.

It is the the same set back as before and yes the 300x weight is slightly more but very close 450-475 lbs That 225 johnson special edtion had a lighten cowl.

Masser do you know of any one with a Scorpion Eliminator or has had one. Need some feed back

thanks

Steve

[stokernick]

Steve,I have a '84 stoker and after sending pics to Alan he told me I was running the engine too high.I seemed locked in on the 1/4 to 1/2 above the pad theory.I've found level with pad or just below with neutral trim lifts me level,and no porpoise!

[stokernick]

2.4 BP offshore 28 lightning ET & 28 Mazco RE 6800rpm's

[scorpion300x]

Steve,I have a '84 stoker and after sending pics to Alan he told me I was running the engine too high.I seemed locked in on the 1/4 to 1/2 above the pad theory.I've found level with pad or just below with neutral trim lifts me level,and no porpoise!

Stokernick ill give that a try today at the Ct river.

thanks for the advice

Steve