A: "What prop is best for my boat" again :) 2300 SR 5.7 efi - Maxum Boat Owners Club

don_her · 04-17-2012, 02:28 PM

As the topic title suggests,

I'm having a hard time to choose a prop for our boat. It's a Maxum 2300 SR, 1998, with a 5.7 EFI mercruiser and alpha one drive. I don't know what ratio this drive is, or how to find it? If i'm correct this is a 250hp engine.

Currently we're using a high 5 prop, but i'm not to pleased with pick up nor top speed. (37 mph with 3 people onboard, half tank of gas.)

I've been reading sooooo much about props, i simply don't know what to do anymore :s

Who has real hands on experience and performance figures for this boat? And perhaps some other ways to increase performance for this engine? Any input is greatly appreciated.

shrew · 04-17-2012, 03:09 PM

Max RPM for that model is 4800 to 5200. What are your average RPM's at WOT? What are you referring to when you say 'Pickup"? Is this getting out of the hole and up on plane from a dead stop? You should remain within your MAx RPM range. That being said, you are going to trade hole shot for top speed. Better hole shot, lower top speed. Higher Top Speed and slower hole shot. Everything in between is a compromise.

don_her · 04-17-2012, 03:34 PM

Hi, with pick up i indeed mean starting from dead stop or walking speed.

Out of the top of my head, max rpm was at 4800rpm, but could also have been 4700 bit in doubt there. The boat will be put in the water again in about 2-3 weeks so than i can test again to be sure. I'm supposed to get a call later this afternoon of the people where the boat is in the winter for the details of the current prop.

edit:
And i thought for this engine the rpm's were 4400-4800? Thats what i get when i search the web

Edit2:
Just got a call back from the people who service the boat, it currently has a 13.25x19 high 5 prop fitted.

seapuppy · 04-17-2012, 04:40 PM

welcome to the zoo....the standard carbed engine is between 4400-4800 rpm wot...the efi or mpi engines are 4800-5200 rpm depending on where the rev limiter is set.....so if your running the efi engine...you should hit wot at about 5200rpm.....anything under that ..your over propped....anything over that your under propped.....nobody can give you exact numbers cuz you need to go by what is wot....do you have trim tabs.....use them to help get out of the hole...do you run with the drives all the way down out of the hole and then bump the drive up as you get out of the hole??..that can affect the performance too..

a few other things to think about....is the hull clean..???...engine in tune....gas fairly fresh....??...all of these factors can affect the boat's performance...

SP

don_her · 04-17-2012, 04:50 PM

Ok, i will look into the rpm's when the boat is back in the water.

Boat/hull were clean, gas fresh. The hull is cleaned every year and antifouled.

Usually from dead start either the trim is at it's lowest or a tad above the lowest position, once the boat is on plane it's trimmed up to get it more out of the water. The boat does not have trim tabs installed.

tjwieseler · 04-17-2012, 06:53 PM

If this is a 5.7 TBI EFI it is 4400-4800 WOT

See attached
Mercruiser Service Manual _17 page 1B-8.pdf

Mercury has a really good Prop selector tool on their website

http://www.mercurymarine.com/propellers/prop-selector/

don_her · 04-17-2012, 09:13 PM

Yes, it's a Thunderbolt V EFI.
I've walked through the prop selector a couple of times, unfortunately it doesn't have the info on our boat

I've tried to enter as much as i know and then it gives about 8 possible props. (un)fortunately, not the one we have.. So improvements should be possible

Does anyone have any performance figures with different props?

Furthermore, is this the engine on which it's possible to gain about 20-30hp with different exhaust manifolds? Sounds a bit to good to be true to me

But i was looking at the IMCO marine Thumper Power exhaust kit, http://www.imcomarine.com/cal_store/...kit-black.html or the http://www.imcomarine.com/cal_store/...m-mercury.html

Will these give a noticeable increase in performance, and also finally release some of the V8-gurgle? Now it almost sounds as a sowing machine... My 4 cilinder 3.0 mercruiser sounded more dangerous lol

shrew · 04-18-2012, 08:36 PM

I found a number of links that also state max RPM is 4400-4800. I'll recant my previous statement. You're already at the top of your max rpm range, so you're not going to be able to do much for hoel shot. Increasing pitch will increase top speed but decreawse holeshot. Does this boat have trim tabs? Are you working the outdrive trim as well. Trim tabs would help get on plane faster as well. Almost 40mph with that boat is not bad. You could probably eek a bit more out of it. How many seconds to get on plane?

I don't think performance exhaust is the way to go. No offense, but this simply doesn't sound like the boat for you. A cuddy is not really a performance boat.

don_her · 04-18-2012, 09:20 PM

Cuddy?? It's a bowrider

(SC is cuddy, we've got an SR)

Personally i don't think i'd have picked this boat... But it's my dads and now basically me and my brother have got it at our house. He uses it about 1 or 2 times a year. And well, we just would like a little bit more 'oomph'

It's without trimtabs. Once we've picked it up from the winter housing i'll do some tests on how many seconds it takes to get on plane and what rpm's it really does at WOT. I always use the trim depending on what we're doing.

ss3964spd · 04-18-2012, 10:03 PM

Based on the performance of my 2400 SC3, which has 50 more HP, a B3 drive, but is a little heavier, your boat ought to do mid 40's for MPH and get on plane in probably 5-6 seconds with a light load. Try to find out what the original prop specifications were and work from there.

don_her · 04-19-2012, 09:19 AM

I will try to get the exact specifications of the boat and original prop online later today.

I was thinking of getting this prop:
http://propulse.se/english/2011/12/08/9902/
It's 14,5x14-22 pitch. That way i could set it at low pitch when we're boating on the lake at our house, and simply increase the pitch when going for longer trips. Any experiences with these?

Also i'm still thinking about the exhaust system, the extra power would be welcome but even more to get some better sound out of the engine, anybody has experienced the differences with the systmes i mentioned? I understand most people online here are from the USA, so are very accustomed to having the V8 sounds, but where i live V8's are not so much used so we still get enthused by a good sounding motor

Edit:
From what i can find online, the original prop was 15x17.

seapuppy · 04-19-2012, 04:54 PM

oh no man....I wouldn't run that on your boat...pick a good prop that's suited for your engine/drive and check the WOT rpms...then change the prop if need be...but those plastic props are not durable enough for your boat.....you couldn't give me one of those..

just my 2 braincells firing off some...

SP

don_her · 04-20-2012, 09:55 PM

We're going to get the boat this sunday, so i hope it'll be at least dry outside! We'll put some fresh gas in it have a nice warm up and test speed/wot and maybe even change with a spare prop that should be in the boat.. We'll move on from there then

CountryME · 04-22-2012, 05:20 PM

don_her,
If you're looking for more performance for a smaller investment, get yourself a set of smart tabs. http://www.nauticusinc.com/smart_tabsSX.htm Got mine at amazon.com and they are way less than a new prop (about $150 for your size boat) and made a big impact on getting out of the hole and overall performance. I too considered a different prop and decided on tabs instead. Just my $.02

-JP

don_her · 04-23-2012, 12:16 PM

To be honest, the smart tabs sound 'to good to be true'

But it might be worth a try.. I picked up the boat yesterday but due to weather conditions and other activities i did not have the chance to do some test runs, but did get the boat to reach 70km/h on the gps with it's current prop. (43,5mph) So this was quite a bit faster then what we noted down last year. The engine has received a service/tuneup this year and it did seem to accelerate faster as well. I will keep you updated when the weather is a bit better and i can test the boat a couple of times and with different props!

don_her · 05-02-2012, 09:08 AM

Finally i've had some time to test the boat as it is; we've been busy moving some stuff and the weather was not good enough to go out with the boat. Then also the windows of my brothers car got smashed in and thieves stole our laptops from the trunk so i had to search for this forum

So here are the current specifics:
The boat has a 13.25x19 high-5 propellor and it does 68km/h at 4200-4300rpm. (42mph)
From standstill to plane is 6,5 seconds.

I was thinking of trying a 14,5x21 3 blade or 4 blade prop to get some more speed out of it.

jrings · 05-02-2012, 02:08 PM

Just to throw my $0.02 in... I have a 2004 2400SR (bow rider) with the 5.7L 250HP Carbureted motor Alpha outdrive. I just checked the other day when I was putting my prop back on after winter layup and it is a Michigan Wheel part number 993053 which is a 14-1/4" (diameter) X 17 (pitch) stainless steel. I can't tell you exactly what the RPM's are at WOT but with 3 adults half tank of gas pretty calm lake I can hit 45MPH or so. This will only be the second season with the boat for me and I am pretty happy with hole shot and top speed. I was initially very concerned about top speed prior to getting the boat because my old boat with a 454 big block would do 55MPH with no problem and I had been able to hit 62 a time or two... This boat is quite a bit bigger and heavier and I am considering smart tabs to help at the low end... For what its worth, thought this might be some helpful information for comparison sake...

Jerryh3 · 05-03-2012, 11:24 AM

I have the 2300SC and run a 19P 3 blade. It's the 250HP Carb version, but I can run 42 WOT with 3 people on board.

don_her · 05-03-2012, 11:26 AM

My run was done with me and a friend (we're both XL so lets say 3 ppl for the math

) and half a tank of gas.
Might be a nice idea to get this setup:
http://marine-performance-parts.com/hipsbcm.aspx

And then keep this prop.

Huddo007 · 05-03-2012, 03:23 PM

Don_her,

I have gone through this process with my 215 bayliner I ended up with 4 props, one for wakeboarding, 1 for skiing, one for slalom and one for cruising at low RPM or super fast top end, let's face it, Less than 5 minutes and you have changed them over to get the best from your boat - BTW have done the multiple prop (plastic) at 165hp I was flexing it so would never attempt any bigger