242LS prop choice - cruising, speed
 

Hi,

Thought I would start another thread to discuss props.

I have a 1989 242LS with a 454 magnum (365 HP)

I'm running a SS 21P mirage prop. (part #48-13702 A40; what does the A40 mean? I've seen different suffixes for this part number)

At WOT, tabs up and drive trimmed I'm seeing 53mph on GPS. This is with 3/4 fuel and 2 people. The tach shows 5300+rpms which is too much; book says max RPM should be between 4600-5000.

I'm thinking about trying a 23p mirage prop. (Would I get a mirage or mirage+, what is the difference?)

What are other single big block 242LS owners running?

Top speed isn't that important as I wouldn't keep it at WOT for long, but rather I'd like to bump up my cruising speeds in the 3000 to 3500rpm range.

Also, how long is it safe to run at WOT? ("until the motor grenades" Yeah I know that, but really, how long do you run at WOT?)

Chuck

Chuck, Right now I am running a bravo 1 4 blade 22 pitch, but I had it labbed by houston prop. All trimmed up I will get 4600-4700 rpm, with a nice cruise around 3000-3200. This prop gets me out of the hole pretty nice with good control in cornering.

Hope this helps

mark

ps At least you`ve had yours out already.

Mark,

4 blades, interesting.

What speeds are you seeing at the top end and cruising?

And I'm sure MA will warm up sooner or later!

Chuck

I have had really great results with the Michigan Ballistic Prop. They seem to have a lot better hole-shot and better top end also. As a matter of fact Houston Propeller has their own design which from what I can tell is somewhat similar. I think it's a cross between a Mirage and a Ballistic they call it the Accellerator I think. Most people really seem to like it. When I can afford it I plan on shipping mine out.

BH

Chuck, From what I can remember cruising is in the low 30`s top is about 61mph sorry not gps numbers. Give darin a call at Houston prop he can help you out. The one thing you will need is seat time just to get the feel of your boat and where the trim feels right. Top speed in the 242 should be about 63 max unless your running sum big power. Remember play with your trim and your tabs the boat will respond very nice.

Hey Chuck it`s not easy being the small guys on the board.

Yeah, trim tabs are a new toy for me, and I'm looking forward to more seat time and burning more gas. It would be nice to cruise at 35-40mph (on calm days).

The Bay is getting "smaller" with a bigger boat. Last weekend we drove from my marina to Annapolis, MD in 20 minutes; with the old boat it took 45 minutes, mostly because we had to go real slow in rough water.

Yeah, but at some point everyone was a new boat owner or owned a "small" boat. I would like to think of this boat as the step between the 18 Sea Ray and a 30 or 35 Formula. I told my wife that we would try the Formula to see if we like performance boats and the next one could either be a Sea Ray Weekender or a sport boat with twin 454s. Last weekend she pointed to a much bigger formula that passed by and said "we should get one of those." The seeds have been sowed!

IMMEDIATELY, get down on your knees and praise the Lord. You have just successfully cleared the largest hurdle in offshore boating, wives.

Chuck,

I'd suggest either a 23 standard Mirage, or a 21 Mirage plus. The Mirage plus has added cup, so that is why you would go smaller. Those 2 props are fairly common, so maybe a local shop will let you try one. You could try a 22 bravo 4 blade as well.

I had a 24' performance boat with similar hull and weight as a 242. and the same 365 mag package. The 23 standard Mirage was the right prop for that boat. RPM's averaged from 4900-5050 depending on weight and conditions.

Hmmm... I actually have a 23 Mirage still lying around somewhere that I could part with. If you end up going that route drop me a PM if you want and we possibly could work a deal.

LOL!!! No kidding. But honey, the superchargers need a bearing freshening and a polish:D !

I went ahead and bought a 23 mirage plus prop from a local supplier.

With 2 people and 3/4 fuel I could only spin to 4200rpms trimmed out @ 54mph GPS. I used more trim but then the prop broke loose and I slowed down considerably.

Good news is that the cruising speed has gone up. 3200 rpms with some trim and tabs down a bit to keep the nose down put me at 34 mph. I am now getting some "porpoising" without running tabs in the midrange. If I give it more throttle, 3500rpms and above, the ride flattens out.

Prop supplier suggested that I try a 4 blade 22 pitch bravo prop.

Shoot, I read this message too late!

OK, I'm starting to wonder if my prop supplier knows what he is talking about.

I wonder if a 23 mirage (NOT PLUS) would have been the perfect fit.

private message
 

I received your message ,give me a call when you can,Darin 10:00-10:00 7 days a week

Chuck try the 4 blade you will love it Darin can help with this.

That's what I said above. You probably need either a 21 plus, or 23 mirage. Again, Merc added more cup to the newer plus models, so you typically go down 2" in pitch compared to the standard Mirage. Any Merc prop dealer worth his salt should have known this.

So a 23 Mirage plus is more like a 25 Mirage. Return that prop, 4200 is way to low, and is overburnding the engine. In my opinion, it is better to be a little too high on RPM's than too low.

As mentioned, you could try a 22 4 blade if available.

Jaybird,

OK, now I get it. And I had read your post after buying the 23 mirage +. It wasn't clear to me when I bought it that was what I was getting so I asked for clarification (after the fact of course). Prop supplier responded to me to say "all mirage props are plus. that is the new style. the plus has extra cup as compared to the first generation mirage" Wish he would have told me on the front end! Oh well.

OK, well I'll definitely have to make a change and let you know the results...I'm think this boat should do 60mph with the right prop...

Chuck

Re: 242LS prop choice - cruising, speed
 

I returned the 23 mirage plus and I'm going to try a 22 Bravo I four blade next.

Last weekend the temperature gauge went up after a cruise. Mechanical pulled the water pump to find the impeller had disintegrated. It's always something :)

So hopefully I can try the four blade this weekend.

Re: 242LS prop choice - cruising, speed
 

I ran the 4 blade bravo 1 today. Topped out at 55mph @ 4800rpms trimmed out. Acceleration is better and the boat gets on a plane much quicker. Runs about 34mph at 3200rpms. Boat handled the waves better too which I don't understand. Oh, and no "porpoising" with this prop, when I ran the 3 blade mirage+ the boat was jumping out of the water at mid range cruising speeds.

Re: 242LS prop choice - cruising, speed
 

Sounds like you've found the right prop. 4800 is right in the middle of that engines WOT operating range. 4 blade props "hold / grip" the water better, which can improve your ride. Also you are probably running a different trim angle with this prop, which also affects handling.

Well with a new water pump and prop, sounds like you're ready to go boating!

Re: 242LS prop choice - cruising, speed
 

I should be getting the 22 pitch bravo prop soon. The one I tested was a test prop and was painted blue of all colors. Got all kinds of comments about it at the boat yard. Hope to be on the bay this weekend.

Two weeks ago I burned up ANOTHER impeller. I was running the motor on the rack and the flusher thing wasn't on there correctly.

This time I changed it myself. Hopefully I was able to get the water pump on there right. Just as I finished installing it last weekend it started to rain, so I didn't get to go for a test drive.

Re: 242LS prop choice - cruising, speed
 

I just got a GPS unit thru work so I thought I would see what speed I am getting with my 242 454 mag w/alpha 4 blade bravo 22 labbed, I saw 55 GPS.I am a little disapionted but I guess this is very average .


Thanks for listening

mark

Re: 242LS prop choice - cruising, speed
 

Thats one nice looking four blade,Masi 242.Thanks and Have a great 4th

Darin

Re: 242LS prop choice - cruising, speed
 

I am seeing 55mph gps with 22 bravo I and 454 magnum.

Great prop, good accelation and handling.

55mph is pretty quick in a 242 LS and a chop...faster I'd want something bigger.

70mph in a 30' formula....that's what I'm talkin about.