View Full Version : props/speed

08-01-2010, 04:47 PM
I am new to this world. Bought my 18 classic about 2 months ago and love it. I already know after reading forums a general consensus of thru hull exhaust so I will save that question. Basically my 2 questions are 1)what is the best prop for overall speed/fuel efficiency/control? I am running 21p 4 blade prop right now and it seems like top end it is rev'd out. GPS at 56mph 2) i noticed after finally getting comfortable with the sheer performance of boat pretty much after 3/4 throttle it feels actually slower as if it is bogging or almost just over spinning if that makes sense.
I have read through alot of posts for last week but didnt really find my answers. Thank you

08-01-2010, 08:45 PM
What engine do you have? 56 sounds way low regardless.

08-02-2010, 06:21 AM
How many RPM?

08-02-2010, 06:54 AM
I have a 5.7 FI Chevy vortec. Its a nice motor. Like I said its usually 4200-4300 and 3/4 throttle. When i have gone full it seems to rev up but not do much more almost like it is overspinning. But I usually have my wife wit me and the St Johns river is kinda ripply. So maybe I need to go out without the wife and with a little more testosterone and see what it can do. It is def a different world at 55 in the 18 and even 85 in the car. But any suggestions will be appreciated. I guess I will go out on a flat day this week and trim it out a little more and hope for the best:) but i have been told a 3 blade 23p prop would be a difference on speed and rpms? Im very sure it will do more than 56, cause the motor is quite and it seems to have alot of hidden power just waiting.

08-03-2010, 02:11 PM
as if it means anything the current prop measures 14" and is marked 48-825904A45-21P any recommendations on switching?

Last Tango
08-04-2010, 06:28 PM
21P is too small for your boat, and on the St. Johns. I recommend a 23P Mirage Plus. That is what I used so effectively on my 18 on the St. Johns. You will be slower on a flat day. 6" ripples are the best. The late afternoon seabreeze will be a little rough once it fills in.e best

You didn't ask but,
Best place to boat and eat is Whitey's Fish Camp on Doctors Lake. Second Best is Clark's Fish Camp on Julington Creek.
Hooters: San Jose the water can be very shallow at their fingerpiers.
Hooters: Downtown the Landing is a tough place to tie up when the current is running.
OutBack Crabshack - long dock, sky high prices, mediocre food
Corkey Bells - Palatka - short dock but deep both sides. Good food and fair prices. Nice run from Jax area.

08-04-2010, 09:22 PM
Well thx man. Actually was out at whiteys and black creek last weekend. I am familiar with all of those places and have aleady been to aloof them with exception of palatka. I was actually looking at a couple 23p mirages on craigs list. Will I really lose top end? Well I'm quite content at 60mph just trying not to have it reved out. But it looks like 23 is what alot are running with a stock mild motor

08-04-2010, 09:27 PM
you need a23 Turbo 1

08-04-2010, 09:27 PM
And to correct myself on ripples. I guess I mean when you get to the deeper parts that have more of wave that tends to give you a little launch feeling under your a$$. The wife really gives me a go to he'll look as she holds on for dear life lol

08-04-2010, 09:30 PM
Thx Grizz. I tried to send u a message seein that every one seems to respect and take your advice. Should I search craigslist or you have connections? Thx

Last Tango
08-04-2010, 09:45 PM
Grizzly IS the connection for Turbo props. He can hook you up directly.

08-05-2010, 09:49 AM
You have mail

The Hedgehog
08-05-2010, 10:20 AM
you need a23 Turbo 1

+1, My X-18 loves that prop. Ask anyone that drove it last weekend

08-05-2010, 08:10 PM
I think we need to know the RPMs at WOT with the current prop and the gear ratio of the drive in addition to current speed at WOT.

08-07-2010, 05:03 PM
Well today till my garmin took battery dump. WOT 4500 rpm 58gps
Like I said 4 blade 21 pitch trophy prop. Stock alpa 1 outdrive. not sure of gearing. Actually a little dissapointed even though my bud has a 25 ft deckbout with a 454 and volvo dupprop he said when i passed him he was doing 52 at 4000 rpm.

Barry Eller
08-07-2010, 08:38 PM
Is your avatar photo of your boat? The photo looks like a boat with too much negative trim...

08-08-2010, 12:00 PM
You are trimmed too low, but that is the wrong prop for that boat.

Greg Guimond
08-08-2010, 02:13 PM
Grizz, what is the difference between the Turbo 1 and the Turbo Fusion 4 ?

08-08-2010, 09:10 PM
Well yeah I was low in the pic cause a friend was taking pic couple weeks ago and was trying to keep from porposing. when you say negative trim you are meaning down to low correct. I usually have it 3/4 meaning first line up from bottom on trim guage, anything higher i hit a little wake and bouncy bouncy. Where should i be trimmed at, and thx grizz working on getting new prop.

08-08-2010, 09:25 PM
The Turbo 1 is a 3 blade round ear prop that does not work well in elevated drives..

Barry Eller
08-09-2010, 10:34 AM
Well yeah I was low in the pic cause a friend was taking pic couple weeks ago and was trying to keep from porposing. when you say negative trim you are meaning down to low correct. I usually have it 3/4 meaning first line up from bottom on trim guage, anything higher i hit a little wake and bouncy bouncy. Where should i be trimmed at, and thx grizz working on getting new prop.

No one position is correct trim. Trim for different conditions and loads. Trimmed down is negative trim...up or trimmed out is positive trim. Trim changes the angle of attack of the propeller to the horizontal or horizon. Most boat owners manuals say to trim to the point of neutral steering torque. You can't feel steering torque much with power steering, but when you trim up/out the steering wheel will have pressure coming from one side and as you trim the drive down it will change to the other side. Finding the sweet spot in the middle takes seat time. To go faster...trim it out...this takes seat time to know how far you can trim before it becomes counter productive. Trim down for rough water and planning with heavy loads, etc. Again...seat time...learning your boat.

08-13-2010, 03:03 PM
Well I borrowed a Mirage 3 blade 23p today and ran it. I was running WOT at only 4k rpms hammer down. I was running 58-60 still. Is that normal considering I see alot of people running 0ver 5k on rpms. More blades? I noticed compared to other prop it was a little more squirrly and hole shot dropped noticeably? Any recommendations which direction as far as pitch or blades? Or should I realize this is probly a good thing considering the limited options and $$ i have put in so far??

08-13-2010, 07:55 PM
Grizzly IS the connection for Turbo props. He can hook you up directly.

Fixx too! :)

And lakeside..

Last Tango
08-13-2010, 11:07 PM
Well, you keep referring to 4000 rpm as the max you can turn. I believe the engine you are running has a max rpm of about 4400 rpm +-10% which means you may be there on this engine. Speed sounds about right for the props and drive you have, though we don't know all of the conditions. Gear ratio of the drive is important info. Altitude above sea level, air temperature, salinity of the water (fresh water is slower than brakish or salt water because there is less bouyancy for the hull, thus more drag). Your engine timing, fuel settings, quality of gas (pump gas from gas station contains ethanol which is not a performance enhancer for gas engines unless they have been specifically tuned for that). And the trim settings. And maybe your hull has too much hook in the stern from spending its life on a badly fitted trailer. Yep, lots of potential reasons.
So there is no one specific silver bullet for your speed question. You need to work on learning about ALL of the items above. Props are but just one piece of a large and complicated jig saw puzzle for best boat speed for your specific boat.
And SEAT TIME is the best way to start learning. Make only one change at a time. Try it more than one outing before moving on to the next change.
You asked about props, and almost everyone gave you prop answers. It may not be just the prop...

08-14-2010, 09:43 AM
I have re read everything in this post. I think with the vortex you can do close to 5000. The first prop you has was too small in diameter, the M+ is loose up top and i think the tack is off. Something is not right here. Now too much trim and the prop spins free and does not pull.

08-14-2010, 10:25 AM
Well thanks for all the input. There is no doubt I probably need MORE seat time. I guess I was just kinda asking questions as they came up. I understand that the pitch lowers RPMS and it make sense that I have seen on my motor it avgs mid to high 4s on rpms depending on prop. Grizz I will check all wiring and tach today and tomorrow, thx for input. I will also take prop off and check hub is intact. I did notice a difference in props when it came to trimming. Once again thx for all the input and feel free to post any thoughts. Ryan