Rinker captivia 206, to prop or not to prop

[Cj7jeepoffroad]

1) My boat seems to run the same speed (55 MPH) no matter if I have one person or five people in it, Do i need more prop?
2) Auminum, Merc?
3) 14.25"X21P
4) 4600-4800RPM, 55 MPH, loaded or unloaded
5) 350ci, Alpha MR (1.65:1 I think), 280ish Horse power
6) 1988 Rinker Capitiva 206, 20.5', no idea how heavy.

 

[steelespike]

Re: Rinker captivia 206, to prop or not to prop

Is your speed by gps? Is 4600 loaded rpm and 4800 unloaded? My info indicates ratio is 1.32.
Calculator says 22% slip at 55 @ 4800.Thats a lot.

 

[Cj7jeepoffroad]

Re: Rinker captivia 206, to prop or not to prop

Im sorry, I just checked and its a 1.5:1

 

[steelespike]

Re: Rinker captivia 206, to prop or not to prop

Thats a more reasonable 13%.Is your speed by gps?
While a little outside high normal 13% doesn't indicate a prop change
and isn't likely to make a significant change.

 

[Cj7jeepoffroad]

Re: Rinker captivia 206, to prop or not to prop

Yes I have verified my speed-o with GPS.

 

[Cj7jeepoffroad]

Re: Rinker captivia 206, to prop or not to prop

Do you guys think a new prop would help? I just dont understand why I dont loose any speed when I load the boat up?

 

[Cj7jeepoffroad]

Re: Rinker captivia 206, to prop or not to prop

geeze, did I **** some one off?

Im thinking a Mirage Plus 14.75" 21"p? Am I on the right track?

 

[Bondo]

Re: Rinker captivia 206, to prop or not to prop

geeze, did I **** some one off?

Im thinking a Mirage Plus 14.75" 21"p? Am I on the right track?

Nope,... answers take time, this is a forum, not a chatroom...

Donno why you don't see the effects of added load,... kinda odd...

 

[Philster]

Re: Rinker captivia 206, to prop or not to prop

Mirage Plus is for bigger boats and engines (...generally. Everything is generally). If you want an SS prop, well.. um, yeah, since your RPMs are so good, you'd probably want to just match your current pitch. You're complaining about great aluminum prop performance, so the silence might be from... 'well, you have a great prop, but want something else'

Solas Rubex 21p

Stiletto Advantage II 21p

Been hearing good things about the value of the Rubex. Sold on iboats. Check 'em out.

 

[bnicov]

Re: Rinker captivia 206, to prop or not to prop

What are you looking for?? Better speed, better hole shot?? You seem to have a pretty good top speed. You need to be a bit more specific as to what you are looking for. From what you've said thus far, your boat seems to run quite fine the way it is. I don't want to sound like I'm biting your head off but more info is better and the more specific you can be with a question and or symptoms is how people can help you out on this board.

 

[Cj7jeepoffroad]

Re: Rinker captivia 206, to prop or not to prop

Hole shot is the furthest thing from my mind. Don?t get me wrong, I don?t want to take a mile to plane off, low RPM planing, midrange, fuel mileage and as much top end as possible is what I?m looking for.

That's not to much to ask for is it?

Maybe I do have the best all around prop now, I'm not sure???

 

[Cj7jeepoffroad]

Re: Rinker captivia 206, to prop or not to prop

I guess I also should have mentioned that my boat has Vortec heads and a GM performance aluminium intake, qudrajet carb. I think it should have around 280-290Hp?

 

[Cj7jeepoffroad]

Re: Rinker captivia 206, to prop or not to prop

What do you guys think about my setup with a 14" 21p 4 blade aluminum Merc prop, should lower crusing RPM and give better fuel mileage? Shouldnt loose much off top end should I?

 

[steelespike]

Re: Rinker captivia 206, to prop or not to prop

When you have a20 boat that runs 55 loaded or un loaded. I would say your looking for trouble fiddling with the prop.
usually a 4 blade they suggest dropping 1" in pitch to maintain rpm and you will likely lose speed.
Same pitch you will lose rpm and speed.
You wouldn't necessarily want to reduce rpm on a boat that appears to rev freely within its' rpm range.
A 4 blade would probably allow a lower throttle setting reducing your rpm. But the same pitch may further reduce the rpm
possibly making the motor labor slightly.Too much and you could end up with a higher throttle setting for the same rpm.
A 4 blade should have good hole shot.stay on plane easier at reduced throttle and may handle better around the dock.

 

[Mi duckdown]

Re: Rinker captivia 206, to prop or not to prop

I agree with steel. You are messing with success.

 

[Cj7jeepoffroad]

Re: Rinker captivia 206, to prop or not to prop

Ok, ill keep it the way it is and just pick up a extra Merc aluminium prop 14.25" 21" Pitch. One more question though, If I was to switch to Stainless what prop would be best suited to my Boat?

Thanks for all the help.

 

[Philster]

Re: Rinker captivia 206, to prop or not to prop

I posted two in post 9.

 

[Cj7jeepoffroad]

Re: Rinker captivia 206, to prop or not to prop

I posted two in post 9.

Ok cool, so just stick with the 14.25" diameter in stainless?

 

[Philster]

Re: Rinker captivia 206, to prop or not to prop

Yes.

 

[rschap1]

Re: Rinker captivia 206, to prop or not to prop

I had a 92 Rinker 206 Captiva with a 350.
I ran a Merc Laser II.
I got a deal on it so thought I would try.
If I recall correctly it was a 22" pitch.
Prop has a set of "plugs" in the hub that will or will not allow exhaust out and induce cavitation at lower speeds (hole shot).
I think that there even different size plugs to fine tune the amount of exhaust gas/slippage.
I ran w/o plugs. Boat topped out just shy of 60 (gps).
Holeshot and getting on plane were tough though.
With only myself and low fuel it was not too bad.
4 or 5 passengers, it would ABSOLUTELY not get on plane. NOT AT ALL.
I had a 19 and 21 aluminum I used for back ups, skiing, tubing, etc.
But top speed was maxed with that Laser II.
That boat was a light cuddy and I was surprised it got that much speed. It was for sure all the prop it could handle and right on the edge of too much.