bowtie89

Ok with the 25 pitch prop I got it up to about 47 mph much improved over the 40 I messed around with the drive trim and trim tabs. I put on the 19 ptch prop and the boat maxed out at 35 mph screaming if you know what I mean. I this the If I have the prop tuned and repitched to 23 I think I will see speeds into the 50's good day on the water!!!!!!!!

Iggy

47 with a 25" and 35 with the 19"????
Somethings not right. I get 58 out of a 21".
Here's a copy of an e-mail I sent/received from Formula about my prop.
Start at bottom of page and work back up.



Bob,

Here's one answer...

Thanks,

Scott S.

----------
From: Scott Smith
Sent: Thursday, January 24, 2002 9:12 AM
To: Mike Boyd
Subject: RE: F-206LS and Laser Prop

Thanks, Mike. I'll forward this on to Bob.

Scott S.

----------
From: Mike Boyd
Sent: Thursday, January 24, 2002 9:10 AM
To: Scott Smith
Subject: RE: F-206LS and Laser Prop

It looks as though we offered the 19" Laser II for those customers who were concerned more with out-of-the-hole performance, rather than cruise and top-end. We continued to send the Mirage prop out with the boat, but I too recall recommending the Laser II for certain situations.

I couldn't find any TTP numbers, but the Laser II allowed the motor to turn up 4800rpm, producing 55mph.

-----Original Message-----
From: Scott Smith
Sent: Thursday, January 24, 2002 8:58 AM
To: 'Kellum, Robert'
Subject: RE: F-206LS and Laser Prop

Bob,

Glad you're enjoying that 206! That was probably manufactured right about the time I started with T-bird, so the boat cant' be too old or in bad shape. I know I'm not. Ha!

I'm going to forward this down to a couple of guys in our technical assistance group.

Mike/Kerry,

I thought that after running Mirages on 206 LS packages (350 Magnums), we found that overall performance was better with a Laser II. Is that correct? What pitch? And was that with or without the ventilation plugs installed?

Thanks,

Scott S.

----------
From: Kellum, Robert
Sent: Thursday, January 24, 2002 8:48 AM
To: Scott Smith
Subject: F-206LS and Laser Prop

Morning Boilerdaddy,

If your offer still stands, I'd be interested to know if what you said is
true that the Laser II prop was better than the Mirage on the 206 series
hull.
I mentioned in my OSO post that I thought my current Mirage prop, p/n
13702-A40-21P, was the original because of it's apparent age.
This prop is slow coming out of the hole and down right impossible with
three people in the rear seat, I usually have to ask one person to step up
to the windscreen to help get the bow down. Maybe I need more power.

I want to thank Formula for building an excellent product. This boat has
held up beautifully over the years (it was new in '88 and I'm the third
owner). My wife and I love it. Our friends are jealous, they have Bayliner,
Regal and Sea Ray's, and it still turns heads where ever we go.

Thanks,

Bob Kellum (OSO - Iggy)

mopower

My bet is the 25s are turning way low and lugging the engine. That's why the speed is so low.
For the boat and power a 21" three blade or 20" 4 blade sounds about right

bowtie89

It probably doesn't help much that the boat has about 3 layer of bottom paint on it that is chipping of horribly!! Am I losing anything from that???
I am worried that if I buy a 21 pitch or a 23 pitch prop that my rps will be to high, as it is right now if I get the drive and tabs trimmed right the boat will see 4800 rpm's how high can this 350 magnum go and how long can it stay at WOT???

Audiofn

Yes you are DEFINATLY loosing from that

First there is the added weight then there is the added imperfections in the bottom and lastly it does not release water as well as the gell will. Time to take it off!!! Job sucks but it can be done. I had to do it to my boat.

Jon

mopower

Before you buy a prop , best bet is to ask around at dealers or prop shops if you can borrow one. I know one dealer I used to deal with had a ton of used props. I could try them for nothing just because they knew me , but a stranger off the street could do the same for a refundable deposit...just to keep them honest:rolleyes
I believe Merc has a similar deal , but the shipping will kill you. Better off trying locally.
You say right now you get 4800 max?? That's right in the ballpark for a 350 mag. sounds like you already have a good prop.
How long at WOT? That's one I won't touch A buddy of mine has this thing about WOT...he loves it. and when I finish this response I'm headed over to his place to try to figure out what's wrong with his 406 this time
Myself , I have gobs of hp and can run 3000 prm and 50 mph all day without beatin' on the engines. I generally only run them WOT for less that a minute. If someone wants to play , thats all it takes to see "Who da Daddy is"

bowtie89

ok I got the rpms checked and the tachometer is dead nuts!!! now what do I do???4800 with a 25 pitch what is going on now I will get a gps and see if the speedo is acurate

mopower

Now it's 4800 with a 25" prop?? That seems high for a 206 with a 350. Iggy's numbers are right where they would be expected. I had 25's when I had 454's in mine and 4800 would yield near 70 mph.
Sounds like your prop hub could be slipping , possibly. Unless it's a solid hub. The only other possibility would be if the drive had been changed and was not the normal 1.5 gears that V8's have. six cylinders and 4's have lower gearing...that too could be messing you up.

bowtie89

How can I check the gearing in the drive?? Will it be listed on it or is there another way I can check without cracking it open?? I am getting so frustrated with this, but the way you are talking about this drive thing its about the only thing that makes any sense!!
Also should I have the boat bead blasted or sand blasted?? and once that is done I should wet sand the bottom to get it all the same color again?? blasting it will leave imperfections or at least thats what I heard?? Is that the best way to go about doing that??
thanks alot you guys you are a big help!!! Without this forum I think I would be LOST???

BAD-HABIT

Ive told ya "something ain't right"....NO WAY your turning a 25p prop 4800....AGAIN.....NOOOO WAAAAAY...check your ratio to be sure but I doubt it has been changed...Now if your motor was built up MAYBE you could turn that...You need to make two phone calls...One to Formula and find out what prop came with the boat and what kind of rpm's you should get with it. Explain your problem and get some answers....Second call whoever makes your prop and get their take.....I ran your figures and came up with 60%slip...Now maybe your prop has been reworked down to a 23. With a little work to that you might be getting close to your numbers but you still would be pushing 30+% which is still waaaay out there.....If it was me I would 1)check the coupler/and gear ratio....2)install a new,2nd tach and check for accuarcy. 3)Take the prop to a local shop and have the thing checked for pitch and the condition of the prop hub. 4)call Formula and your prop manufacture with your findings....
Try this calculatro to get an idea of what type of rpm's and speed you should be getting with your prop and rpm's
www.go-fast.com/Prop_Slip_Calculator.htm

Good luck and don't give up......

BH