Is my prop right???

[St1977]

Owned this boat about a year, 2004 sea fox 257 cc with 200 mercury efi saltwater series. 0t789145
motor has 260 hours on in and runs great.

however at wot, I can only manage about 4700-4800 rpm after trimming up until the boat starts porpoising. I read that 5000-5800 should be wot. Top speed on a flat lake is 38mph according to both gps.

The prop that is on it now is a vengeance 48 16318 21p

am I missing any speed here at wot? Boat seems to plane ok when loaded with 4 people, 150 gallons and all fishing gear. Got 36mph loaded. although I don’t have any other boats to compare to.
should I leave it alone or try a different prop.

thanks for any info.

 

[jimmbo]

I will assume the engine is a 2.5 liter
The Prop selector chart I consulted(mercury) show 17 or 18 inch props, depending on which line of Props.Dropping to a 17 would add 800 - 1000 rpms which would place you where you want the engine to run.

Since you have only owned the boat a year, I will assume that was the prop that was on it

 

[St1977]

It’s a 3.0 liter, and yes this is the prop that came on it when I got it. The engine is a 03 model so I don’t think it is original, and the cover says 225, but looking up parts by serial say 200

 

[jimmbo]

The way merc has done the Serial Numbers is, they have a group of Numbers, say F0200000 - F0325000 for year X. That range of numbers will show up in all the HP groups for that Model Year.


Merc made several 3 liter models

Comercial
Hi Performance
Optimax
maybe a couple more.

 

[Fun Times]

St1977 The serial number has your engine to be an MERCURY 2003 3.0L EFI SALTWATER 225EFI XL SW model number 1225423AY... The 200-HP and 250-HP's just shares the same parts guides as your 225-HP... On some parts guide websites it's easy to over look what engine model you may truly have.

Also it's not unusual to see a engine year model differ from the boat year model by a year or 2 so your engine "may" still be original to the boat.

Being an 2004 you might still be able to confirm by using your boats hull ID number you could probably call or email sea fox to see what engine model and serial number came on your boat from new and what prop they'd recommend using as it's usually listed in their notes regarding the sale of the boat from new. And since you question the engine not being original I'd also ask if the engine and boat combo works well with your "XL" which = a 25 inch shaft so you know if the shaft length might be affecting overall boat and/or engine performance or not..., http://www.seafoxboats.com/

Also at this time this seems to be more of a prop question, so lets move this topic up into the Prop Questions and Topics vs being here Mercury & Mariner Outboards

Thanks jimmbo and good luck St with getting your boat back up to speed.:encouragement:
https://www.perfprotech.com/mercury-marine-parts-catalog/umodel/20827

 

[dingbat]

Know your boat/motor combination well.

Your over propped. Most running that combo are running 14.25 x 17" or 15 x 15" props

 

[Sea Rider]

That notor could be over propped or current prop could be on its way to become fully spun, check condition with a slip hub test before going to less pitch props if wanting the motor to rev towards its max wot rpm range as loaded.

Happy Boating

 

[Faztbullet]

Sea apparently you don't under the concept of a spun hub...if hub is failing RPM will RISE and speed go down

 

[dazk14]

That's too much prop for that rig. You didn't mention the condition of the hull...painted..anti-fouling, condition?

 

[St1977]

That's too much prop for that rig. You didn't mention the condition of the hull...painted..anti-fouling, condition?

Hull is in good condition, not painted. Kept on a trailer.

 

[St1977]

Thanks for all the suggestions, should I go back with another vengeance?

 

[jimmbo]

You have a few Options/Choices from Mercury, Vengeance is one of them,

I chose the Opti as it was the only 3 liter that was offered in both 200 and 225

Engine: 225 Optimax.
Drive / Gear Case: Large OB 200-300 HP 1.75 Gear Ratio

Black Max®	Mercalloy	3	16	16	RH	16440A45
Black Max®	Mercalloy	3	16	16	RH	16440CP1
Black Max®	Mercalloy	3	15	17	RH	832828A45
Black Max®	Mercalloy	3	15.5	18	RH	11324A45
Mirage® Plus	Stainless Steel	3	15.5	17	RH	18278A46
Mirage® Plus	Stainless Steel	3	15.38000011	18	RH	889620A46
Revolution 4®	Stainless Steel	4	14.625	15	RH	857022A46
Revolution 4®	Stainless Steel	4	14.625	17	RH	857024A46
Vengeance®	Stainless Steel	3	14.5	17	RH	16314A46

 

[QBhoy]

Thanks for all the suggestions, should I go back with another vengeance?

Stay well clear of a vengeance. It’s nothing other than a shiny looking version of a standard black max. Not performance attributes to it at all. In fact any test I’ve ever seen shows the ally black max out perform it too. With your set up, I’d be investing in a proper stainless bigger diameter prop like a tempest plus or something. Of suitable pitch of course. You want that kind of prop to be able to lift that big hull out the water. A vengeance will do nothing for you at all.

 

[St1977]

Found a mirage plus 17p used. I’ll post results after I install and try it out.

 

[dingbat]

Found a mirage plus 17p used. I’ll post results after I install and try it out.

If your run a good bit offshore as I do, you might want to look at the Enertia as well.

I reduced my fuel consumption (at cruise) by 10% going from 14.25" x 17" Offshore Renegade to a 15" x 15" Enertia.

 

[dazk14]

The Mirage will give very good stern lift for a 3 blade. It also has quite a bit more diameter to help push that big rig and hold plane, cruise efficiently. It'll be interested to see the top end speed trimmed out.

 

[St1977]

Update........

I got to try the 17p mirage plus out today.

I need to change what was in original post, top rpm with the 21p was 4550 on VesselView, this was Saturday when we went fishing. Top mph was 35.5 with the 21p. This was with 4 people and a few fishing poles.

today, with 3 people
results are WOT 4950-5000 rpm, 39.5-40mph, 24.8 Gph, 4200 rpm 32mph 17.5gph 3600rpm 26mph 14.2gph
At WOT, I trimmed up until the boat started to porpoise, then back down a little. Or putting the trim tabs down a little cured it and only hurt mph by .5.

it takes off a lot better than it used to and also steers better while docking. Motor even sounds better at cruise speed.

thanks everyone for the help, I got the prop for 180 plus shipping so I think that was a great deal. Could probably still use a 15p or so, but it’s a different boat with this one.