ISO of 580 DB Props

[RMervyn]

I have an 05 550/580 DB.

Current props are 28 x 35 x 2.5, the boat needs a little more aggressive prop as i need to run a higher RPM to make the same speed and the load is always much lower.

Original props were 28 x 37 x 2.5, which i also still have but were shaved down to 27's due to repairs over the years.

The factory props on a buddys '06 were 29.5 x 35.5 x 2.5
and another buddy has an '07 with 30 x 33 x 2.5

For some reason, searay changed the props over the course of the build... all with CRM 900 Mans. That being said, looking to preferably find the 29.5 or 30 inch iterations if anyone has a line on some.

Thanks in advance!

 

[TNT8808]

I would suggest checking in with Ben at Holland Propeller if you haven't already.

 

[carterchapman]

I had my 30 x 33’s set to 30 x 32.7

 

[ttmott]

I have an 05 550/580 DB.

Current props are 28 x 35 x 2.5, the boat needs a little more aggressive prop as i need to run a higher RPM to make the same speed and the load is always much lower.

Original props were 28 x 37 x 2.5, which i also still have but were shaved down to 27's due to repairs over the years.

The factory props on a buddys '06 were 29.5 x 35.5 x 2.5
and another buddy has an '07 with 30 x 33 x 2.5

For some reason, searay changed the props over the course of the build... all with CRM 900 Mans. That being said, looking to preferably find the 29.5 or 30 inch iterations if anyone has a line on some.

Thanks in advance!

Before you get too crazy can the engines pull their maximum rated RPM with the props you have? Do the engine's hit their rev limiters? If so what is the hull speed at the rev limiter? Boat fully weighted (fuel and water)? Clean hull? This is the data needed with the existing propellers a good prop guy needs to size a replacement set. Sea Ray had a propensity to over-pitch the propellers on the larger boats, so I'd be cautious defaulting to the OEM spec.

 

[ranger58sb]

The props we have mounted came to us as 30x33s. We re-pitched them to 30x31s this last Spring after most current sea trails and WOT test.

Don't know what our spares are yet; haven't re-looked at those to see if they're the originally spec'd 28x37s or the replacement 30x33s.

-Chris

 

[dtfeld]

You probably get a lot of cautious advice when talking about propping your diesel powered Sea Ray. A lot of us have ended up taking pitch out of the props with the goal of extending the life of the engines we have. There is some science to it.

If you follow Tom's post above and get some WOT numbers with the boat loaded as you would normally cruise the boat (typically full fuel, water food people dinghy etc), you can put those numbers into a prop calculator and see if you are over/under propped. Typically, you want to be a little under propped, so your not lugging the engines. Over propped is generally bad for marine diesels lifespan. If you wan to go faster for a given RPM, you'll need to lighten the boat (less fuel, and stuff on the boat).

Tony over at sbmar.com has a lot of info on the subject, so google him, but here's a primer. -->https://www.sbmar.com/featured-article/propellers-move-boats-engines-just-turn-them/

Here's what it looks like in practice Only difference is the MAX RPM at WOT...

 

[RMervyn]

Thanks for the advice.
Boat could hit max rpm with both props I’ve tested but the factory set was much higher on load at cruise. The props pitched to 35 were not putting a full load (80%)on unless the boat was full of fuel and cruising at higher rpm’s.

what are your thoughts about the progression that searay used, going from 28 to 29.5 to 30 inch props as the years went on?

 

[carterchapman]

what are your thoughts about the progression that searay used, going from 28 to 29.5 to 30 inch props as the years went on?

My understanding was the original 28X37's were cavitating and burning the blades and hubs. Sea Ray switched to 30X33's in 2006.