What Size DUOPROP?

[shulerville]

I need an Answer TODAY! I have a 1998 Wellcraft 260SE with Volvo 5.7GS an OD with 1.95 ratio. The drive is a remanfactured with no props. Volvo nor Wellcraft has helped me. What size duoprop should be on this boat? I have to make an expensive decision today. Any help would be appreciated.

 

[steelespike]

Re: What Size DUOPROP?

Under the cercumstances I think you need to find a dealer that will let you try props for the right selection.A sizeable deposit will be required with the understanding you will be purchasing props.What is the weight of the boat?What props were on it before?
Considering a pair of matched duo props must be 500 or 1000 dollars depending on the selection Its hard to imagine a dealer to expect you pay for props till you or they get it right.
Have you tried to find a wellcraft or volvo forum for posts on similar boats/props?
Hopefully some one will be along with more help.
If I had to guess I'd lean yoward a 17" or 19" pitch.Thats assuming a full blown cruiser.
I usually suggest if your guessing to go one inch less because if you end up oversize you
you'll lug the motor.(not good for it)

 

[Maclin]

Re: What Size DUOPROP?

The Volvo DuoProp sets are not sized by inches of pitch, they are in a number series by type of prop (alum or SS) and Volvo has not given an x-ref that I know of.

Your setup should be D series for Aluminum and F series for Stainless. I have attached a PDF document for the prop guide from Volvo, you would look in the D and F prop sections for your engine (5.7GS) and you will see the speed range for each numbered prop. It is not real intuitive, but you basically find the top speed range for the boat and see what numbered prop covers that range. For your boat, I take it is a 26 footer, the F5-F7 range would be in the ball park. F7 may be too tall, F5 would probably work well. Look up other boats like yours in web searches and see if the propset size is given, that would give some clues as to what the boat would have come with.

I have aluminum B5's for an older drive, and using real world numbers (RPM, Speed, ratio) they calculate to a 21 pitch with 8-10% slip. When I ran B7's that calced to about a 26 pitch. The stainless steel prop numbers were about the same.

 

[Maclin]

Re: What Size DUOPROP?

Shuler, I meant to add this to my previous post...


If I had to get one TODAY for that boat (assunming heavy cruiser), and no other option, like a gun to my head, I would go with F4's.

 

[shulerville]

Re: What Size DUOPROP?

Thank you fellas for your quick response. I did not believe how difficult it is to size a duoprop to my boat. The dealer that sold me the OD is now trying to use his sources to figure out the correct "F" duoprop. I can't afford to not get it right. Thanks to all who chipped in. I will let ya'll know after Christmas.

 

[shulerville]

Re: What Size DUOPROP?

Thank you so much Commander. I now have a chart showing all the differences between "D" and "F" for my engine. I wish I had this chart 2 eeks ago. Thanks again!!!

The Volvo DuoProp sets are not sized by inches of pitch, they are in a number series by type of prop (alum or SS) and Volvo has not given an x-ref that I know of.

Your setup should be D series for Aluminum and F series for Stainless. I have attached a PDF document for the prop guide from Volvo, you would look in the D and F prop sections for your engine (5.7GS) and you will see the speed range for each numbered prop. It is not real intuitive, but you basically find the top speed range for the boat and see what numbered prop covers that range. For your boat, I take it is a 26 footer, the F5-F7 range would be in the ball park. F7 may be too tall, F5 would probably work well. Look up other boats like yours in web searches and see if the propset size is given, that would give some clues as to what the boat would have come with.

I have aluminum B5's for an older drive, and using real world numbers (RPM, Speed, ratio) they calculate to a 21 pitch with 8-10% slip. When I ran B7's that calced to about a 26 pitch. The stainless steel prop numbers were about the same.

 

[Maclin]

Re: What Size DUOPROP?

Good deal!

This is a great forum, you will be glad you joined.

Welcome Aboard Mate!


Disclaimer:
Thanks for referring to me as a Commander, but lest I be exalted in your realm beyond normal courtesies, the Commander is a title based on number of posts here...