Props in or out on a trip
 

Gentlemen I was hoping someone could give me some idea on props in or out. I have a straight bottom 43 Scarab with trip 850's & #5 drives & 17x31 4 blade props. The nose cones are roughly 3.5" below the running surface of the hull. I've tried raising the lowers 2" by removing the 2" spacer but that really didn't seem to help & the prop slip went into the 18% range. With the spacer back in the slip is in the 12% range. But the old girls heavy a** feels like it's just stuck in the water. It never really gets loosened up. Any help would be appreated. I have some big tube headers coming & have just installed 10-71 BDS blowers & plan to turn the boast up to 10 psi which should bump the motors up to 950-1000 each. By the way I'm at 92 on gps right now. Thanks.

Re: Props in or out on a trip
 

start with some modern day large diameter 5 blade props. work with a prop shop...i know if you buy props from someone like cobra, you can exchange them.

look under the water line....there is WAY more there to be had than where your currently looking above(ie engine).

good luck

Re: Props in or out on a trip
 

i run mine out 42 fountain triple 540s

Re: Props in or out on a trip
 

O.K. that's one sugestion to turn the props out,thankyou. I will assume audacity is talking about Cobra engines which I'll contact. But how about just telling me what your talking about below the water line I'm not racing just looking for straight forward suggestions.Thankyou.

Re: Props in or out on a trip
 

I'd think again about running 10 lbs boost.....$$$$$$ repairs

Re: Props in or out on a trip
 

bottom of the boat/hull in relation to the surface of the water. also set-up; where the props are in relation to the bottom of the boat and each other. what props. weight...ect

just trying to say, people seem to want to increase HP prior to looking at set-ups and the bottoms.

i would never assume your props should turn one way vs. another without seeing/running the boat first hand. even if i owned the same boat. too many variables.

good luck!

Re: Props in or out on a trip
 

Thankyou for all you guys help but the 10 psi boast don't bother me I have Jack Roush helping me with the motors. As for the set-up I've said that they are 17x31 4 blades & the nose cones are roughly 3.5" below the running surface of the hull. There are no stand-off boxes. I'm not trying to set on the pole at Talledaga I've already done that. I just want to get my boat a little closer than what Wellcraft sent it out the door.

Re: Props in or out on a trip
 

Ran a 36 baja with #5 540 blown 860 hp, had stand off boxes, 4 blade cleavers 2 inch spacers. Took long time to get out of the hole, but it ran faster and better with props turning out, tried in and hard to get out of hole and slower top speed by 5 mph 98 out 93 in. Is smaller boat but may help, bottom was blue printed too.

Re: Props in or out on a trip
 

Thankyou Scooter that is info that I can use even if it's a smaller boat. Thanks again.

Re: Props in or out on a trip
 

what gear ratio...how fast...what rpm...what is your set-back from the running surface...what is the toe-in/out in relation to propshaft centerline...what is it in relation to skeg...what are your props center to center...these all very important measurements and factors.

how is the bottom of the boat...huge variable and can not ascertained via a phone conversation nor here in the forms.

what does it weigh?


JR is helping you with engines? then you are around detroit?

Re: Props in or out on a trip
 

Was this a Larry Smith Scarab?? If so look him up and give him a call. Heck it might be worth a call anyway..... Someone on here will have his contact info.

Re: Props in or out on a trip
 

no problem hope it will help

Re: Props in or out on a trip
 

It's not a Larry Smith it's just a standard Wellcraft. I have Larry's contact numbers thankyou. I don't live in Detroit I'm in N.Carolina. Has for the measurements rpm's currently 5200-5300 I want to turn 6000 gear ratio is 1.5 the toe is set at .062" per side in I have tried it out no noticable change. Set back, I'm not at home I'm in Daytona testing soit & the rest of the measurements I don't have with me. With a trip does props out help with transom lift?

Re: Props in or out on a trip
 

12% is bad a** with a 43 Scarab. Turning out should give
your hull more transom lift.Also check toe in & out on you drives.3.5 " below the running surface seems deep.If you pull
the spacers out try a larger diameter prop.This should free
up the drag caused by the gear cases.If stand off boxes were added you could probably go higher.Talk to the factory about
what your trying to accomplish.92 Looks like about 5400 rpms
1:50 gears, more HP should give you the ride your looking for
Just my 2 Good luck!!!

Re: Props in or out on a trip
 

Thanks Hotpursuit. I just checked my prop slip calculator with the 2" spacer out I had around 18% slip now I'm in th 13.3% range. Which if I could turn 6000 that would be about 100 mph even. So if I understand you when I raise the drives I might need some larger diameter props.

Re: Props in or out on a trip
 

2 props can be hard to come by, let alone 3. put teague on the list of people to call about props too.

is your x-dim the same on all 3? is the skeg on the center? are the rpm's across the board? do you have a delta pad?

Re: Props in or out on a trip
 

Thats correct more blade in the water less gear case = increased MPH & less slip. I'm assuming you running cleaver
style wheels.

Re: Props in or out on a trip
 

Yes the X is the same on all 3 & yes the center drive still as the skeg. The rpm's are close enough to call them the same. I learned with my line of work tachs only good for 50-100 rpms & you can only calibrate them real close for only about a 500-1000 rpm range. I know the 5 boat that Gentry set the speed record in '93 had the skeg removed from the center drive although that was #6 drives.

Re: Props in or out on a trip
 

i guess if i was going to pull a set-up out of a$$ based on the above info; i would look to remove the center skeg, go up a size or 2 (engine dependent maybe +) use 5 blade large diameter props on the outside, remove the spacers on the outside only, turn the props out, use your current 4 blade (at first) in the center to allow min hull disturbance. obviously removing the center skeg would be the last move... i would keep the center a 4 blade and play with diameters and pitch after seeing if it liked the spacer removed.

Re: Props in or out on a trip
 

That's correct Hotpursuit they are merc. cleavers. Thanks for your ideas everyone.

Re: Props in or out on a trip
 

He knows Jack Roush well, has sat on the pole at Talladega, and does a lot of testing at Daytona. Seems to me we should be able to figure out who bjlesl is without too many more clues ...

Any takers?

Racegirl3?

Re: Props in or out on a trip
 

Gentlemen I don't mean to sound egotistical or name drop. I've been very lucky to have had some success in the last 16 years being involved in the Nascar industry 10 of which working for JR. But I've also grown very tired of techanical people when asked what time is it? They want to give a seimenar on how to build a watch. Thankyou you all for your suggestions.

Re: Props in or out on a trip
 

bjlesl,
not at all! i can respect that.

let us know how things work out for the boat. good luck.

Re: Props in or out on a trip
 

We played this same game last season with the re-power and re-rigging on my 1997- 38' Cigarette.We went from 600 to 850hp per side
We started with 1.35 ratio 2" shorter drives and the boat hated them, and that was after trying every Hydro ,Bravo etc known to man.We ended up adding 2- 1/2" spacers 1/2" deeper than stock and she handled great but only netted us 3 mph or 86 vrs 83gps with 500hp added.
We also tried the in out prop switch, a few miles per hr better spinning in.
Thinking we were down on power and assured by my Engine builder that couldn't be the case. He found and fixed a hook on the bottom rear of our hull that I checked and could not detect even with my 6' straight edge ,we immediately netted 94mph gps spinning 30p labbed Bravo I props out.
Prior to my project we received expert advice from two well known Cigarette guru's and were sent in two completely different directions from X dimensions to Props.
If I had to do it all over again I would have had my hull professionally checked out first..Good luck with your rig!

Re: Props in or out on a trip
 

You work for DEI but have Roush working on your engines ?
That outa get them stirred up in the shop ! :D

Re: Props in or out on a trip
 

Thankyou that was an issue I was going to try & check with an 8-10' straight edge. I don't have a lot of time to do the hunt & peck method with being gone 40 weekends a year. I was just trying to narrow down the amount of things to question. Hey, I'd love to trade the old girl in on a Cgarette or Outerlimits. But, I can't come to grips with depriecation into the six figrues & also a 1000 dollars per month insurance. Hell, I barrly have six figrues invested in my whole rig. I know that it's old technolgy but if I can get her to 100 I'll be satisfied at least for now (I thought 90 would also 2.5 yeas ago!). Thanks again.

Re: Props in or out on a trip
 

No Birdog I do not work for DEI.

Re: Props in or out on a trip
 

I saw "JR" & just thought of Dale. Just curious..What team are you with ?

Sorry..Cant help you with the triples..never had them

Re: Props in or out on a trip
 

I'm currently the Nascar program manger for Ford Motor Company.

Re: Props in or out on a trip
 

Cool job....I'm sure all the traveling gets old for you though.

Re: Props in or out on a trip
 

May not be the same for all boats but as a rule of thumb I think if you turn the props out you'll want the toe to be set at 0* or slightly out.

Also, turning out should lift the transom some, and so will a 5 blade but may not give bow lift which could scrub some speed. A lot of times though the older flat bottom boats need bow lift so Larry Smith may be able to help out with prop selection the best.

Good luck!

Re: Props in or out on a trip
 

Thanks Panther. Also the answer is starting my 16th. year traveling full time it gets very old moreso when you have a child & an offshore boat you never see.

Re: Props in or out on a trip
 

Does anyone happen to have a piar of 17-18x31-32's 5 blades that they would like to sell?