Improving the performance of my 36 foot, GRP, production, sailboat.

I saw that Superyachts programme on Quest the other day and they were racing with a grand piano and a cannon on board. They were shifting a bit, so it appears that if you can't lose weight adding seventy feet in length seems to do the job nicely.
 
BAtoo said:
It would be nice to know which boat the OP wants to go faster...........View attachment 33665 or View attachment 33664
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She is a Dufour 365 so definitely a cruising rather than racing boat. Before saying anything else I would just like to say that she is a good boat and am pleased with her but I would like to find, for starters, some of the performance I think we had when she was new. On the sail up Southampton Water on day 1, I mentioned earlier, we held 7.6 - 7.8 knots for extended periods (and touched 8.3 knots) and comfortably held position with a couple of 45 footers for much of the time. I think now we are lucky to hold 7.0 knots with perhaps 7.5 knots max in similar wind strength.

PS The prop is folding - though only a standard 2 blade Volvo.
 
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Ian_Rob said:
Other than changing the skipper - what one change would you make to my boat to make her perform better (sail faster and closer to the wind, etc) and what performance increase might be expected from making that change? She is just over 5 years old with the original, production mainsail & genoa, adjustable (but not cockpit-adjustable) cars, non-adjustable backstays, self-polishing antifouling......
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Glue a bathing platform to the stern to give yourself an extra couple of feet LOA.
 
Ian_Rob said:
Other than changing the skipper - what one change would you make to my boat to make her perform better (sail faster and closer to the wind, etc) and what performance increase might be expected from making that change? She is just over 5 years old with the original, production mainsail & genoa, adjustable (but not cockpit-adjustable) cars, non-adjustable backstays, self-polishing antifouling......
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Biggest improvement to the speed that you can make comes from upskilling the helm and crew. A really good skipper and crew on your boat as it is now would likely beat you and your present crew after buying all the goodies listed above. That said the goodies will help - sails as supplied by the boat builder are selecvted for only one reason, cheapness.
 
Five year old sails originally from the lowest bidding loft won't be helping the cause. All the dressing will have disappeared and you're left with soft, porous cloth which won't hold a shape and won't respond well to trimming. New sails, from a good loft in a decent fabric might be £ several K though. Winter is the best time to get quotes.
 
Twister_Ken said:
Five year old sails originally from the lowest bidding loft won't be helping the cause. All the dressing will have disappeared and you're left with soft, porous cloth which won't hold a shape and won't respond well to trimming. New sails, from a good loft in a decent fabric might be £ several K though. Winter is the best time to get quotes.
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Being fair it's an assumption that the OP has sails from the lowest bidding loft (= assumption that that is the loft of preference for the manufacturer). He says 'production sails' but that doesn't mean manufacturer's choice, or that their choice was bad, and at 5 yrs might still have a suit of fair to excellent sails. You have no way of knowing otherwise and I reckon a LOT of forumites are sailing around with 5+ yr old 'manufacturer's choice' sails that they reckon are good. And why not.....
 
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bitbaltic said:
Being fair it's an assumption that the OP has sails from the lowest bidding loft (= assumption that that is the loft of preference for the manufacturer). He says 'production sails' but that doesn't mean manufacturer's choice, or that their choice was bad, and at 5 yrs might still have a suit of fair to excellent sails. You have no way of knowing otherwise and I reckon a LOT of forumites are sailing around with 5+ yr old 'manufacturer's choice' sails that they reckon are good. And why not.....
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Very true. I'm assuming the worst. Tho' often that's what 'production' sails are.
 
I have read these threads about all the marvellous things you can spend money on in order to improve the speed of your yacht but nobody has mentioned the very cheap piece of tape that you put on the top of the steering wheel to mark when the rudder is inline with the keel. Not necessary if you have a tiller!

If the hull of the boat is going to go through the water fast the rudder should be in line with the keel. (Least resistance to forward motion) As water is thicker than air it is better to get the balance of the yacht right, rather than have the sails set at the exact right angle. So adjust the sails so that the piece of tape is near the centre line of the boat. We have to pull our mainsail up to windward because we have an in mast furling mainsail and we cannot angle the mast further back or the boom would hit the bimini!!

There is much mention of "weather helm" and people seem to assume wrongly that this is to do with the pull on the tiller or wheel. How do you know when you have weather helm? The tape on the wheel will be on the leeward side of the centreline. If is on the windward side of the centreline you have lee helm like us. When setting the sails into balance the feel on the rudder has little to do with it. Once you are sailing the feel of the rudder tells you everything.

Once you have applied the piece of tape then spend your money on the other things. Hope I am not telling people" how to suck eggs" but I have seen so many boats with excessive rudder churning up the water behind them.

Trundletruck
 
TRUNDLETRUC said:
I have read these threads about all the marvellous things you can spend money on in order to improve the speed of your yacht but nobody has mentioned the very cheap piece of tape that you put on the top of the steering wheel to mark when the rudder is inline with the keel. Not necessary if you have a tiller!

If the hull of the boat is going to go through the water fast the rudder should be in line with the keel. (Least resistance to forward motion) As water is thicker than air it is better to get the balance of the yacht right, rather than have the sails set at the exact right angle. So adjust the sails so that the piece of tape is near the centre line of the boat. We have to pull our mainsail up to windward because we have an in mast furling mainsail and we cannot angle the mast further back or the boom would hit the bimini!!

There is much mention of "weather helm" and people seem to assume wrongly that this is to do with the pull on the tiller or wheel. How do you know when you have weather helm? The tape on the wheel will be on the leeward side of the centreline. If is on the windward side of the centreline you have lee helm like us. When setting the sails into balance the feel on the rudder has little to do with it. Once you are sailing the feel of the rudder tells you everything.

Once you have applied the piece of tape then spend your money on the other things. Hope I am not telling people" how to suck eggs" but I have seen so many boats with excessive rudder churning up the water behind them.

Trundletruck
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Very true.However a little weather helm is desirable for feeling.Helming a boat with lee helm is a nightmare.
 
TRUNDLETRUC said:
I have read these threads about all the marvellous things you can spend money on in order to improve the speed of your yacht but nobody has mentioned the very cheap piece of tape that you put on the top of the steering wheel to mark when the rudder is inline with the keel.
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Or put a whipping at top dead centre. Doesn't peel off and stick to your sailing gloves!
 
Twister_Ken said:
Very true. I'm assuming the worst. Tho' often that's what 'production' sails are.
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I think you are probably right in your assumption but again, to be fair to Dufour, you get what you pay for and I bought to my budget. I will read the trimming book kindly recommended, forget about improving the fairing, try and do a bit of of racing with boats of similar type and class, dream of adjustable back-stays and cars, watch the weather helm and loose weight (in all senses).

The sails just suffice for now but the time is fast approaching when they will be replaced and then I am sure I will be just a disappearing speck on the horizon.

Thanks to all.
 
30boat said:
Very true.However a little weather helm is desirable for feeling.Helming a boat with lee helm is a nightmare.
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It's not just feel. The ideal rudder angle for most boats is 5 degrees when going upwind. Having this angle helps the rudder create some lift and reduce the leeway.

On a reach, you should aim for less, none if possible.
 
All good points. Very little to add save that trying to keep the boat as much upright as possible and use the rudder as little as possible. All goes back to good sail trimming and correct interperation of the instruments. ( apparent or true wind etc) Before spending any money to change the sails have them checked by a competent sailmaker and get some advice as to how much are they out of shape.
 
Ian_Rob said:
She is a Dufour 365 so definitely a cruising rather than racing boat. Before saying anything else I would just like to say that she is a good boat and am pleased with her but I would like to find, for starters, some of the performance I think we had when she was new. On the sail up Southampton Water on day 1, I mentioned earlier, we held 7.6 - 7.8 knots for extended periods (and touched 8.3 knots) and comfortably held position with a couple of 45 footers for much of the time. I think now we are lucky to hold 7.0 knots with perhaps 7.5 knots max in similar wind strength.

PS The prop is folding - though only a standard 2 blade Volvo.
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Yes, I'd agree Dufour is a pretty good cruising range for most peoples needs.

I don't think there's much difference in drag between the various types of folders - they are all better in that respect compared with fixed - its their pushing and stopping abilities that differ.

So that leaves the boat excess weight (free to sort), rig set-up (cheapish) and sails (expensive) as presumably your skills are no worse than when you got her.

Here :- http://pdf.nauticexpo.com/pdf/dufour-yachts/dufour-365/20156-4023.html it says your light (unladen) displacement is 6.25T -wonder what it is now??

Has the rig been down since you had the boat & if so who set it up afterwards? If its not been down has it ever been checked/re-set by a (good) rigger?

I've never had 5yr old production sails that I know of but I understand they are built down to a price; certainly the 8yr old ones I had on one boat were carp....
 
Leonidas said:
All good points. Very little to add save that trying to keep the boat as much upright as possible and use the rudder as little as possible. All goes back to good sail trimming and correct interperation of the instruments. ( apparent or true wind etc) Before spending any money to change the sails have them checked by a competent sailmaker and get some advice as to how much are they out of shape.
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Little point. Do you really think he is going to tell you that your are a **** sailor and it is not worth investing in new sails?

Of course not.

He is going to tell you that you are a great sailor and that your existing sails are ****. All you need to do is buy a complete new set of laminates. (He might be right of course).
 
Leonidas said:
All good points. Very little to add save that trying to keep the boat as much upright as possible and use the rudder as little as possible. All goes back to good sail trimming and correct interperation of the instruments. ( apparent or true wind etc) Before spending any money to change the sails have them checked by a competent sailmaker and get some advice as to how much are they out of shape.
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You can't trim carp sails.........
 
In reply to the 5% weather helm suggested by Flaming. Do you angle the keel as well?! The keel and rudder are both foils and work in the same way. I see no reason why one should be angled more than the other.

Trundletruck
 
TRUNDLETRUC said:
In reply to the 5% weather helm suggested by Flaming. Do you angle the keel as well?! The keel and rudder are both foils and work in the same way. I see no reason why one should be angled more than the other.

Trundletruck
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You would angle the keel if it were practical. There have been a few boats with assymetric dagger boards or trim tabs on the keel, but not many. Generally, it is not the sort of thing that would be IRC-friendly.

However, there is a very good reason why you would angle the rudder more than the keel - the rudder lies in the wake of the keel so operates in a disturbed flow. For the same reason when fairing a keel you don't cut off the trailing edge at 90 degs to the fore & aft line as that exacerbates the turbulent flow over the keel.

The 4 to 5% rudder angle close hauled is pretty standard stuff, well researched and well documented in a number of text books.
 
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