Doral Citation Merc. 260 Prop

[Vadimk]

I've got a Doral Citation with a Mercruser 260.
First time running and it would hit about 30mph at 4500rpm.
But this was not wot, maybe 80% throttle.
The out-drive has the 2.0:1 ratio I think.
The numbers on the prop are hard to read (paint) but they should be 48 66 52-1

Edit: Prop diameter is 15.5" (Tape measure)

Length 26"
Beam 8' 6"
Dry weight is about 4600lb
Alpha one lower unit.
Aluminum prop.
1985 I think or there about but lower unit was bought rebuilt.

Speed was measured with the speedometer (forgot the gps) put sins it's not wot can't really be used anyway.

I know the best way to test is with trial and error but I'd rather not purchase a bunch of expensive paper weights, if I can get close then I can fine tune it later.

Tell me if I'm missing something.
Thanks.

 

[45Auto]

Re: Doral Citation Merc. 260 Prop

The only way you will get a good recommendation for a prop is if you provide good data. Otherwise you will be buying lots of paperweights.

You need to verify your outdrive ratio. If it is 2.0:1 then you have a 4 cylinder outdrive on your 260. Your outdrive should be a 1.5:1 ratio. This will have a huge effect on prop size and performance of your boat.

You'll also need the pitch of your current prop. It is usually stamped on the hub of the prop. Sometimes you'll have to take the prop nut and washer off to see it.

An accurate speed at WOT is also necessary to provide a basis of comparison to known performance. In some cases there's not any difference between 80% throttle and WOT, sometimes there is a big difference. No way for anyone here to know. We could guess one way or the other, but that probably means more paperweights .....

 

[Vadimk]

Re: Doral Citation Merc. 260 Prop

I'll be taking it out later this week (maby today) and get you some more accurate speed and tach results.

I can confirm that the lower unit has the 1.5:1 gears (turning the engine over and counting).

The only numbers on the prop are 48 66 52-1.

 

[Vadimk]

Re: Doral Citation Merc. 260 Prop

Using the procedure outlined hear:
http://www.propellerpages.com/?c=articles&f=2006-03-27_manual_pitch_measurement

The prop I have has a 14" pitch so it's a 15.5x14
From what I could find a 15x16 prop is about right.

 

[45Auto]

Re: Doral Citation Merc. 260 Prop

The pitch of your prop will usually be marked on the hub, like in the photo below. It's often underneath the prop nut washer when the prop is installed:

http://www.thehulltruth.com/attachments/boating-forum/90792d1257723904-yamaha-150-prop-img_4712.jpg

It would be best to know the manufacturer's stamped pitch. The numbers on the side that you see are often casting numbers and cannot be referenced to determine the prop pitch. We can always reference any changes to the 14" pitch you measured, however different manufacturers measure pitch in different ways. An incorrect ASSumption in prop pitch will make all recommendations worthless.

 

[Vadimk]

Re: Doral Citation Merc. 260 Prop

To measure pitch I had to pull the prop, it's sitting right next to me.

The only numbers on the prop where under the nut and read 48 66 52-1.

There is a local prop shop that will lend me some rebuilt props to tune, so I'm going to start at a 15x16 and go from there.

I knew it would be difficult to get a good answer because I have little information on my side.

Sorry for any inconvenience.

 

[JBF 1962]

Re: Doral Citation Merc. 260 Prop

how fast should a Citation be able to go?

 

[QC]

Re: Doral Citation Merc. 260 Prop

Depends on the engine package JBF. There are no hard and fast speed rules by boat model . . .

 

[JBF 1962]

Re: Doral Citation Merc. 260 Prop

he said it was a merc 260hp

 

[QC]

Re: Doral Citation Merc. 260 Prop

I guess my point was that his package is not "a Citation" it is his Citation. Maybe 35 MPH. A 260 of that vintage is equal to a 230 today and that's a heavy boat for a small block. He hasn't been back since July, so I think we're talking to ourselves anyway JBF . . .

 

[JBF 1962]

Re: Doral Citation Merc. 260 Prop

Heh, yeah, you're right. Mine seems to think it'll do mid 30's, but how accurate are those speedos? (not very i imagine) I'll get a gps over the winter. That's the only good thing about the off season, it's a good time to collect boat toys ;P