performance improvements

[BarryL]

Hello,

I don't hate my boat, I really do like her. In fact I would like to make some improvements to the old girl and I'm trying top get estimates on 'bang for the buck.' I don't have any illusions that I can turn my o'day 35 into a fast racer, but a 1/4 knot here and a 1/2 knot there adds up.

Assuming a 10kt breeze, can you give give me an idea how much of a speed increase I would gain by:
-removing the fixed 3 blade prop and installing the 2 blade prop that is sitting in the lazarette?
-removing the fixed 3 blade prop and installing a folding or feathering prop?
-having a clean, slime free hull (currently the hull has a lot of slime, some growth, no barnacles, and some weedy stuff on the waterline? (I do plan on scraping the hull tomorrow)
-replacing the 1986 Neil Pryde 150 genoa with a modern dacron 140 genoa. The existing sail has been cared for by Sailcare, but is 20+ years old.

Thanks!
Barry

[Faster]

Well, here's my nickel (btw we're pretty much at par now)

From 3 to 2 blade, hard to say but maybe not enough to make up for the loss of thrust and smoothness, say less than .5 knots in lighter conditions.

From 3 to folder, easily between .5 - 1.0 knots, but at considerable expense, esp with a feathering prop (A 2 blade Max will likely run you a few grand but its the cadillac way to go)

Cleaning the hull another .5 to 1.0 or more if its really bad in the light stuff,

A new sail may improve pointing and balance, and light air performance more than raw speed across the board.

When its windy enough that you are getting hull speed anyway, of course there's not much potential to improve.

[sailingdog]

Faster's got it pretty much covered. What kind of shape is the mainsail in?

[Gary M]

It is an absolute must to have a clean smooth bottom. If you have a build up of bottom paint then getting it all off and then getting the hull and especially the keel and rudder smooth as glass is critical. Keeping it that way through out the season of course helps a lot.

Since you have a two blade prop you might as well try it. For maximum effectiveness you should mark the shaft so that you can align the blades vertically, it helps.

A decent folding prop will cost close to $1k but may well be worth it. You will however get a noticeable drop in forward and especially reverse thrust.

As to the sail it just depends on the condition, it may not be that bad and it is certainly the most expensive. Try the others first.

Good Luck
Gary

[Valiente]

What these guys said. Fair the bottom and get a folder like a Gori for that extra .5 to 1 knot in light air. Assume you need new sails, but if they aren't too far gone, you can go for a recut in some cases. I had racing guys' old sails recut for cruising and that and the folder proved to make a noticeable difference.

Next step: a faired bottom.

[SEMIJim]

The PO painstakingly faired the keel on our boat. The surveyor, when he examined the bottom during the haul-out survey said he'd hardly ever seen a better looking bottom and keel than our boat, regardless of age. Now maybe it's just our boat. Maybe it's the faired keel. Maybe it's the Martek folding prop. Probably it's all of those, and perhaps some other magic. But our boat can do damn near wind speed DDW in light air. When we were out a week ago or so, we had this terrific DDW wing-and-wing run where we were averaging 5-1/2 kts. (Dropping to about 5-1/4, peaking near 6.) I later checked SailFlow. Winds at the time we did this were allegedly running in the vicinity of 5-6 kts. When I later mentioned this to the PO, he told us that was normal for our boat.

Jim

[Sasha_V]

My advie would be(in addition to the above mentioned) is to get your vital control lines all set up to be worked fomr the cockpit. It minimises movement of people on deck while underway ina race, and movement on deck slows you down by rolling the boat into different positions as it compensates for the movement of weight on board.

get people where they need to be and keep them still. Weight above the rudder (Usually meaning the cockpit) is good for the downwind legs, so get people off the gunwhales for that leg.

Sail replacement or re-cut may well be an issue, if your old sail has stretched out and gone baggy, then it will be much harder to flatten and trim it to be a wing shape for flying the boat forwards through the wind on upwind legs. If the sail is a bag, then all it will do is make your boat lean over, without actually going anywhere. I have been on a boat that had one rail burried in the water, straining and pushing like we wre on the cover of a sailing magazine....Only to have the GPS tell us we were doing 2.8knots in 18knots of wind....The mainsail was just totally bagged out and could not be flattened.

Sasha

[BarryL]

For all the information.

The main sail seems to be OK. It is from 2001, full battens, looks and feels OK.

The bottom has a lot of paint build up. The surveyor noted it, the yard noted it when they pressure washed it. I will scrape it when the boat comes out in the fall. In the spring I will fair and repaint.

Since I mostly day sail I'm not real concerned with speed under power. I can easily try the two blade prop next year, and could switch back to the 3 blade if I don't see an improvement. I don't see myself spending the money for a folding prop at this time.

Thanks again,
Barry

[KeelHaulin]

Barry-

On the issue of updating your genoa; upwind performance might be quite a bit better with a new sail. The boat might not go much faster but if your old sail has too much stretch in it then your pointing angle might be bad which can have a big effect on upwind performance. If you are not racing this might not be a big issue.

[Fstbttms]

Cleaning your hull is one of the least expensive, most effective speed-improving things you can do to your boat.

I tell people that you can correct sail trim or rig tension or weight distrubtion or a myriad of other variables on the boat during a race, but every second of every minute, every foot of every mile you are on that race course, a dirty bottom is negatively affecting your boat speed. Would you glue a layer of shag carpeting to your hull and expect to be fast? Then why would you ever consider racing without cleaning your hull?