309 vs 310 Performance

[rpwillia]

OK, by the PHRF these two boats are pretty close. I have the fully battened main which helps me point higher, but I believe the 309's underwater configuration (prop right up against the hull with no strut) is a little cleaner. I remember reading somewhere that the 7/8 fractional rig provides an advantage, that should help offset the reduced performance of the furling main.

What are folks thoughts on this? Last race I was back and forth with a 309 and only through old age (which brings with it wisdom and patience), treachery (I beat him to a mark and cut him off) and some good guesses for conditions (more experience with the tide and wind patterns) did I come out victorious - again. How do I make this a regular practice?

 

[Maine Sail]

309..

The 309 & 310 reside on the same basic hull. Differences are in the rig and prop configuration and slight weight differences. Both have a theoretical hull speed of 6.9 knots.

LWL - 310 = 26' 6" / 309 = 26' 6"
Beam - 310 = 11' 6" / 309 = 11' 6"
Ballast Fin - 310 = 4000 Lbs. / 309 = 4000 Lbs.
Ballast Wing - 310 = 4400 Lbs. / 309 = 4400 Lbs.

 

[rpwillia]

Thanks, but not what I was looking for ...

Maine Sail, Thanks but I knew all that. Here is what I was looking for.

309 has a furling main, I have a fully battened main. I can definitely point up a little higher and get overall better sail shape. What are my best tactics with this.

309 has a 7/8 fractional rig, I have a full rig. What does this buy him versus the full rig and do I need to think about alternative tactics.

309 and 310 underwater structures are similar, but where the shaft exits the hull on the 309 there is a nice structure where the prop shaft is partially protected and it looks like the 309 gets better flow and less drag. On my 310 I installed a line cutter which has added drag and I also have a strut that also induces drag. When racing should I let my prop freewheel (Universal Manual sez it is OK), 309 has a Yanmar which generally stats it is a no-no.

General observations are OK, but I am looking overall to step up my competitive game and avoid DFL'ing. I have been following the talk on the ask all sailors forum for the adjustable genoa cars and am pretty sold on them (even have the Admiral thinking they are a great XMAS gift for the guy who has almost everything like me) and in the last race had some nice success using the traveler to adjust for weather helm. That is the kind of stuff I am looking for.

 

[Stu Jackson]

But -- underwater structures???

The underwater differences you describe will have nothing to do with what you do with the gear you have above the waterline: sail trim & tactics.

The big plus you see on the prop arrangement is not so good for the 309. I feel the strut is better because it's simpler and the cutlass bearing is not tucked mysteriously inside the hull. I recall the early 350s had lotsa trouble with engine alignment and noise with that arrangement. I know some other Catalinas have it, but I'm glad I don't.

Maybe some more drag with the strut, but you have your stuff down below, so does he, and it isn't going to affect your racing: sail trim & tactics.

 

[Tim C350 April IV]

Not an engine alignment issue

Stu - Respectfully, the early C350's did not have "lotsa trouble with engine alignment and noise" - particularly as a result of the underwater configuration (strut vs skeg).

The issue (which turned out to be prop cavitation) is explained by Gerry Douglas (Catalina Designer) in this link:
http://www.catalina350.net/phpBB3/viewtopic.php?f=13&t=138

For what it's worth, my C350 was delivered with a fixed 2 bladed prop - not the 3 bladed prop that Gerry mentions, and I never had any of the noise/cavitation issues that some other owners experience. Catalina is also pretty careful in its manuals to stress the importance of correct engine alignment in all of it's models.

Your points about the C350 cutlass bearing being "tucked mysteriously inside the hull" could be clearly countered with an argument about your strut "hanging out there in space, just waiting to come loose, and exposing your shaft to any deadhead that comes along.....", and being exposed to heightened alignment issues due to the extreme distance between the stuffing box and the cutlass bearing/prop.

The original post is about what can the OP effectively do - if anything - with what he has. His clarifying questions like "prop freewheeling or fixed" are the type of discussion he's looking for.

Good Luck!
Tim Brogan
April IV C350 #68
Seattle

 

[Stu Jackson]

Thanks, Tim

Wider blade, same diameter, resolves cavitation? Hmm. Glad it got resolved.

I still feel the clearances provided by the strut between the prop and the hull, while creating more "stuff" underneath, makes me more comfortable that the "strut-less" design.. I know, I know, the extra "stuff" needed to support the strut is another potential point of failure...Struts support the zincs on the shaft between the stern tube and the prop... The list goes on.

I guess the attempt to avoid the strut and leave the cutlass bearing in the "deadwood" is a centuries long ongoing design discussion.

Again, thanks for correcting another one of my numerous misunderstandings about your fine boat. I should study more, and spout less. But you know that already...

Back to the subject? Sure, still: sail trim & tactics.

I think the question was put backwards. After all, what's left when you take out underwater stuff and rigs? That's why they made PHRF to begin with, so what's the question?

Maine Sail already answered the free-wheeling issue.

How do I make this a regular practice?

Keep racing, you have the right attitude. Consider it a one-design and sail fast and sail smart.