Noob - prop question

[Salap178]

I purchased a 230 Overnighter - 1996 with just 200 hrs on her, heated garage stored all her life and i just love her. The Back to back seats is exactly what I was looking for. Great allround boat.
- Good for 30 mile offshore fishing(Anti freeze cooled sys)
- Good for overnighting
- Wake boading is still a question

So I was having a problem with sluggish pick-up and backfiring etc. So I took it in to a dealer and they replaced the timing board and that fixed the ping and backfiring issue. The dealer was not happy with the way it came out of the hole and asked me to bring it back later, My kids needed the boat for their honeymoon.
So they thought maybe it was a knock arrester issue ? could that be?

I think trim tabs will help, so I will install those for next year

My buddy asked what pitch my prop was , I have no idea.
And if i did know , i would have no idea if it was good or bad, hehe.
here is the label on my stainless prop:
310-689-1970
Power Tech Propellers
Un200OFS3R21P
9345243

Does that mean its a 3 blade 21 pitch.
what pitch would help me out of the hole faster??

With the current prop I can cruise at 30mph at 2500rpm, top out at about 48mph ( per GPS and speedo)

please tell me what kind of prop would be good,
Oh my engine is the 5.7 ltr or 350 cu in. electr ignition and fuel injection.

Oh, we use the main engine to troll, out in the Ocean, with the swell and currents , its hard to steer with a kicker, So @ 800rpm I am trolling at 3.1mph, I would like to go slower, so will that hole prop help me slow down at low rpm?

Your insight will be appreciated.

My dealer is over 1.5 hrs away , I'd rather have a more local guy fix it, but I want to sound like I know what I am talking about, hehe.

I used to be a boater , but have not had a boat for the lat 30 years , just getting back, hehe

 

[EricW]

What are your engine RPM's when running at top speed?

 

[berth control]

I just looked at the sea ray prop chart and they don't show a 1996 230 overnighter. Are you sure this is the model and year? Look on the back of the boat and the hull ID will be stamped into the transom. The last two numbers are the year and the model number is usually at the beginning. A 230 overnighter will prob. start with something like SRV230OV....
The obvious solution would be to use a shallower pitch prop, but like Eric asked, if your current WOT RPM is where it should be, a shallower prop will cause the motor to over-rev at WOT and the boat to go slower at top speed. A shallower prop would be like a 19 pitch, steeper would be a 23. The shallower prop would make you troll slower and get on plane faster, but if you are currently getting the ideal wot rpm's the shallower prop would hurt overall performance.

 

[eman369]

After exhausting effort in this category for myself your prop is a 15 1/4 3 blade and yes the pitch is 21 if your rpm's are at spec. For better hole shot move to a 4 blade 15 1/4 and pitch 18-21 you will not be overall faster, but you will hole shot faster and plane faster the pitch is the number of inches moved per revolution the size of the blade controls rpm's if your top rpm's are around 4000 then dropping your blade size to say 15 your rpm's would be about 4200 or there abouts.I hope this helped
Ps. your WOT should be right around 4600 ideally

 

[Salap178]

Thanks for input, when the gps tops me out in the mid to high 40's mph , my rpm is still below 4000, around 3600-3800. So there is room to increase with a lower pitch.

I decided to be more pro-active and check sites like Mercury Marine
and yes , they do not list my 1996 230 OV , but that is exactly what it is. I have select pages of the owners maual in a binder as well, from the original Owner.

The serial number on the transom is SERA08270696 SRV230OV

So that is wierd that Mercury Marine does not list this particular boat to look up the stats, but when i searched the Owners Manual (for the pages that I have) it lists a few 19pitch props , so the previous owner must have switched it out to ctuise faster.

I am wondering if I should drop to a 17 pitch.
I read that you may gain 200 rpm per 1 pitch, so at say 3700 + 800 would be 4500 rpm at top speed

is that over reving that 5.7??

 

[EricW]

Based on your boat and engine specs, I would expect you to reach at least 4400 RPMs with a 19" pitch prop.

However -- since you are only able to reach 3600-3800 with a 21" prop, you do need to drop all the way down to a 17" pich prop to reach the recommended WOT range of 4400-4800 RPMs.

Four things to verify before deciding between 17 or 19" pitch prop:
-- is the hull bottom clean?
-- is the boat carrying any excessive weight or waterlogged?
-- is your tachometer accurate?
-- is your engine in good health and in a good state of tune?

If all those check out, get the 17" pitch. If you can correct any or all of the above, maybe you can run a 19" pitch and get the WOT RPMs up to at least 4400.

I suggest a Mercury Vengeance or Silverado SS prop.

 

[Salap178]

ok Thanks for all the great advice. I ordered a 15.25x17pitch 4 blade stailess prop.
I am also going to search for trim tabs:
18x9 Bennett , Is what I am thinking about, they will also help me out of the hole and keep me running better in rougher water, as well as keeping the boat level when everyone wants to sit on one side, hehe.

 

[Salap178]

Thanks EricW
I installed that 17pitch 4 blade SS prop and took her on a test run yesterday.
Hit 46mph (gps) at 4600rpm WOT. Fantastic ( i think i could have have gotten a little higher mph and rpm with more precise trim but i get nervous at WOT so did nt want to hold it there for too long.)

came out of the hole nicely, responds to the throttle waaaayyy better.

my only issue is that it went from 3.2 mph at 600rpm to 3.9 mph. i was hoping it would have went the other way!

I guess i need that kicker to troll with, hehe or maybe install trim tabs, or both , what do you think?

 

[320Bob]

Thanks EricW
...my only issue is that it went from 3.2 mph at 600rpm to 3.9 mph. i was hoping it would have went the other way!

I guess i need that kicker to troll with, hehe or maybe install trim tabs, or both , what do you think?

Why is going faster at idle an issue?

 

[EricW]

Why is going faster at idle an issue?

Well, I guess he's one of the few that fishes on his Sea Ray. It sounds like he needs to keep his trolling speed down.

The new SS 4 blader is biting harder at idle, pushing you faster.

Trim tabs won't make a difference at idle speed. I have seen a device that you can attach to your lower unit that will slow your idle speed. When lowered, it blocks some of the prop thrust. When you're not trolling, you can raise the device for normal operation. Do a search on the internet and I'm sure you'll find it.

 

[Salap178]

Yes I fish offshore and in lakes with the sea ray
ideally i need to go 2.4 - 3.0mph out on the Ocean for kings silvers and Halibut
1.0 - 1.5mph on the lakes for Kokanee and dollies

I figger to get a 9.9 kicker with electric start and remote steering( I need the alternator to recharge batteries for downriggers, I typically fish offshore at 165 feet down, takes lots of juice)

Another Option my Bud came up with is to get a 15 pitch 3 blade cheapo prop just for when I go fishing, but that will not get me slow enough for the Kokanee