Need different prop?

[mboy]

Since I bought boat in June, I have always had feeling that it should top out a little faster then it does.

Johnson 175 V6 Loop charged 2 stroke (2003) on a 2200lb boat (2003 sea boss 210cc).

Properly trimmed, following sea 2 people half tank I had her up to about 38-39mph.

Engine high rpm range is 4500-5500 according to manual.

Opened her up this weekend again and rpm @ WOT was 5000.

Do I have wrong prop on her (I have NO idea what prop is on there other then it is a 3 blade).

I would like to have prop that gives close to max top speed for boat with best fuel economy.

WOT @ 5000 doesn't seem right to me in any case.


Thoughts?

[Capt. Ed]

Hi Mboy,

With a proper prop, you should be able to achieve (or near achieve) WOT. I have mine set to hit WOT - 200 rpms with full tank of gas (120 gallons) plus one person.

If you remove the prop, the size of the prop is stamped on it, usually on the side closest to the lower unit.

I went through the pain of buying a few until I got one thta works. Unfortunately, now I have props that eventually will be thrown away.

If you find a prop company you like, call them up and they can talk you through the process. Having the size/pitch of your current prop is important. I can take a picture of where the numbers are from one of my props if you would like.

Good luck and good observation,

Ed

[mboy]

Tanks Ed. I probabvly won't be able to loook at my prop until she is out of the water for winter.

I will probably take it off and mayube speak to PJ over at Port MOnmouth marine and seek his help on finding right size.

I know nothing about selecting the right one or going about it.

[CapBob]

Mboy

When you read the size of the prop on the hub it is diameter followed by pitch ie 16 1/2 X 21 (16 1/2 inch diameter and 21 degrees of pitch)

A degree of pitch is worth about 200-300 RPM's depending on boat & motor, cupping the prop blade is same as adding 1/2 degree of pitch, adding/subtracting diameter also adds/subtracts RPMS.

Take good notes on your load engine RPM's and what your speed is.......this will direct you on proper prop sizing (did this for over 18 years)

PJ would be a good source or try a GOOD prop shop.

If I can be of any help give a shout

[Luna Sea 5]

my friend has the same size boat, Seaswirl cuddy, and has a 200 Yammy on it.  He tops out at about 45 mph....  Yours does seem off a bit, but not by much.  The prop size matters, some are built for speed, some for torque, some for top end...  If your lacking speed with your prop, your probably gaining something else, like fuel economy, or a qucker plain.  There are many props designed for what you want.  So, its not like you have the wrong one, just maybe the wrong one for top end.  

[Luna Sea 5]

then again, last year one of my engines went down and I had to get back on a single engine, 175, good thing was, I was in the bay on flat seas.  Planning was a pain, but once I got it there, that one engine did me about 32 mph.. which wasn't that bad...  You should be maxing out close to 42 would be a good guess from what I have seen in the past. 

[mboy]

Once I figure out what size the porp is, I am going to take you up on that Bob.

I know what she does speed wise at various RPM's in comperable water.

About 28-30mph @ 4200 RPM.

Cruise about 3800 RPM @ 25-26mph.

[salty pig]

so you haven't lost rpm's correct? ... mine 21 they say not to go over 150hp my buddy was losing RPM and it was barnacles under his boat guy next to me also had same thing. just a thought

[mboy]

No. Not loosing RPNM's, they were never there.

Even when I had boat surveyed and sea trialed (2 days [literally] after fresh bottom paint and I was there when they dropped boat in water 1st time since winter storage) it only pulled 5000 rpms. Even says in my survey.