bens87241

OK i am sure this is topic the ppl get tired of talking about. but any help and advice would be nice. My boat is a 1987 four winns 241 liberator with a stk 454 330hp motor and someone put a bravo 1 on it( thank you to whoever did that ). The motor runs strong and no issues there. The prop on my boat by then number is an older mirage( not the plus ) 21 pitch 14 3/4 inch dia. Last year the boat would do about 48mph most day while running 4400ish rpm. Now my drive is the 1.5 ratio bone stk motor, rpm is right one checked it agains two tachs, that gives me about 17 percent of slip. i normaly run my boat with about 50 gals of gas and 3 to 4 ppl on board. i know libs are heavy boats not sure what it is exactly.

The prop was real suzzy looking so i had it polished and balanced at a local but prop shop that has a good rep. now the motors goes to about 4500 but the boat only goes 40mph like 33% of slip.

props i have tried the stk 13 3/4 21p 3 blade stainless that came with the boat. last year it turned more rpms with less speed i have 13 3/4 23p 3 blad al. tried it ove the weekend, blew it out of the water getting on plane, eased onto plane finaly got it up running 4000 rpm at 25 mph and the first 3 foot wave caused it to blow out.

I am not an expert but it seems like i need more blade area on the water not really more pitch.

I was thinking some kind of 4 blade.

Now i know 4 blades tend to loose a few mph over 3s for me that is not the biggest issue. I know this boat should run 50ish and i am fine with that. i need a prop that gets me out of the water fast, we have some shallow spots. I do not care its stainless or al, as long as if its stainless it has a rubber style hub. i can see points both ways on both type. for shallow an al with help protect my bravo 1 but with the stainless the soft bottom and small twigs and that wont chew up my blades. ultimantly a 150 buck prop is alot cheaper that bravo 1.

I boat on lake erie so we do get some good waves. so i cant be right on the edge i need a prop with some grip

any idea or sujection would be great. or any idea to WTF might had gone wrong when the shop polished the prop and it to loose that much mph because i sure thought a good polish job would help that prop grib the water seeing how much left over marine growth was stuck on it.....

with your idea and sujections please tell my why you think this would help. not just list me props, i like to know why things work and dont work.

thanks for the help and info

Mr Maine

Did you let the prop shop know that when you dropped it off you were 48mph@4400 and when you got it back you were 40@4500 (lost 8mph)?

Are you trimmed up enough?

You definetly need diameter to carry the heavy boat. I would say the mirage 21 was close. If the shop could have trued it up and got you a mile or 2 an hour that would be 50mph and I would say that is really good for that boat with that power. There was one of those around here would run mid 40's with the 330 but wasen't necessarily dialed in.

I have always heard that liberators like michigan ballistic props.

bens87241

i am running it just how i did last year. I have tried trimming from the bottom all the way till the prop looses grib on the water. surprising it makes very little differance at all. i can feel the nose come up some, but the rpms might change 200 and the mph does not really get any better. i have not gotten back ahold of the prop shop yet justtring to figure out for sure if it the prop that is the issue or not. I was looking at some 4 blade al just to try for cheap, but they are all almost all 14 dia not sure thats the way to go

bens87241

have you heard of just the smaller libbys liking these or is it most of them. has anyone out there libby or not used one how did it work for you

01scarab29

call power tech props ( www.ptpropeller.com ) great information ,,, bet they will surprise you , doesnt cost a dime to call and ask

onesickpantera

iTrader: (1)

Unless they raised the drive and engine when they swapped to a bravo you should not need a 4 blade prop. Look for a Mirage Plus, Ballistic or other bow lifting 3 blade. And stick with SS as you lose a ton of performance with aluminum.

bens87241

I do not think they lifted anything. I am 6'4 and when at the beach in water in about belly level if my drive is down there is only 6 or so inches below the prop. so the prop is every bit of 2 or 2.5 plus feet down. not sure if this helps my last 241 libby had the same motor and alpha drive it had the factory 13 3/4 21 pitch prop the boat would not hardly come on plane and once there had a hard time pulling any real rpms maybe 3700.....i put a 14.25 19 pitch 4 blade on it and the boat ran tons better came on plane nice and ran about 52. now this same prop that i could even come on plane with last year when testing the boat would about 4800 but less mph than the mirage 21. so to me that means more slip so i sold the prop. Now to me if i can spin and slip a prop on this boat that my last boat could not hardly turn the prop i used on that boat would more than likely not work either.

I talked to hill marine and he recomened his signature pleasure 5 blade in either 19 or 21 pitch. He said try the 19 first if not enough he would exchange it to the 21 as long as not damaged. Does anyone know anything about these props or use them?

fleg1

I would say that boat should have a Mirage or Mirage plus in a 21 pitch.. Are you sure the engine is tuned???

BBCLiberator

iTrader: (2)

Before I did anything I'd try a prop that you knew was right and untouched. Borrow one if you can, should be lots of people in your area that can help. If you are getting those RPM's and speed I don't think it would be a spun hub on the prop, but I suppose stranger things have happened. If the data is right they would have to do some pretty major work to screw it up that bad.

There is a prop shop in Gibraltar (the name escapes me right now) that actually has some loaner props and will let you try them out. I would think a 14.25-14.75x19-20 pitch prop should be about right on that boat if everything is in the stock location with a 1.5 ratio drive. Your rpms will bump a bit, but the holeshot will be way better (tolerable) than with a 21".

I also agree with above, there is no need for anything more than a 3-Blade on the boat, seems like everyone with a Liberator with a single has good luck with the Ballistic for some reason...including me.

bens87241

yeah that is one thing i am sure i am an auto tech and build alot of custom cars and drag cars.... the motor is tuned up motor issue is one thing that i do know and know i do not have any of. motor purs at nice 750 at iidle, plugs look great, newer wires and cap. timing spot on to factory spec, thunderbolt box giving proper timing, no bogs, no gas smell, starts every week with only 1 half pump, holds a solid 40 psi oil pressure when running and 20 when warm idle. If i was having lack of rpms i would look tune up issue.....i am getting too much rpm and not the speed to match the rpms


It has enough power to turn that mirage 21 to 4700-4800 but i dont gain any mph with the last few hundred rpm so i pull it back the mirage 21 i have now is just slipping really bad. I dont know if the shop that did the polish jib actualy polished the cup off some what or not.... i found a friend of freind that is going to let me try his mirage plus 23 i think it will be to much pitch and be slow out of the hole but if my rpms are down and my mph is right it will let me know that they turely screwed my prop up i figure if i can only turn that prop even to 4000 i should get somewhere near 50mph with a normal slip number i figure it should be slow out the hole.

my main concern is not really the total top speed cause i dont get much time to run the boat there. its my cruising speed last year was 30mph at 3000 to 3200 depending on water. now to get 30 its like 3500-3600 i thought the prop had slip issue last year. my cruising speed showed like 23-25% slip and 17% on top end now its mid 30% all the time

I guess if with this prop i still get crazy slip numbers i need to look at my coupler alot of work just to take a peak.

I want to say thanks for the help and ides