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 Post subject: A few thoughts on performance
PostPosted: 24 Nov 2020 14:00 
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Tactictian

Joined: 06 Aug 2020 09:02
Posts: 102
While I dig deeper into all my projects, I've done enough sailing on the T37 now to have some opinions on performance. As a racing sailor, I'm always looking to wring every last once of performance out of a boat even while cruising. To that end, I've come to the conclusion that the T37 greatly benefits from a hydraulic backstay regardless of the fact that you are lucky to get 1 inch of bend from the mast. The headstay tension control and resulting control of the headsail shape make it worthwhile. I have found that I can drastically change the draft location and depth of my cross-cut foam luff roller furler this way and it is especially beneficial while close hauled. In addition, I found that while the initial stability of the T37 is not great because of the higher VCG, once heeled the boat stiffens up considerably because of the high ballast/displacement ratio. Therefore, we can hold a decent amount of sail and I am not considering a reef or reducing the headsail until upwards of 15 knots true wind while close hauled and more like 20 cracked off. I therefore had North Sails design me a new mainsail with "max roach", adding nearly 6" onto the leech in the middle of the sail. I also had them increase the hoist and went with full battens and loose foot. The added power provided by the depth in the lower third of the sail is significant. And, even with the extra area, I find that the boat still balances out quite well and I don't have excessive helm with a full main, which can be controlled with some twist (the mid-boom traveler is very effective). To maximize shaping control I added purchase to my outhaul and ran the control line back to a cam cleat in the cockpit. I also added purchase to a cunningham which is still on the mast for now. I removed the small winch for the board control line and added a cascading purchase that can now be hand-tended. This makes it easy to adjust the board on the fly and I find that the board makes a massive difference in helm feel and steering characteristics. The other thing I did recently that is really nice for driving is replace the standard Edson 36" wheel with a Lewmar folding 40" wheel. This wheel allows for much more comfortable driving positions being 2" further outboard and alse dished aft. Of course, a feather or folding prop is a must in my book. I use a MaxProp 3 blade feathering. This winter I will remove the board to conduct maintenance on the pennant, conduit, and thru-hull hose. I will take the opportunity to fair the board with templates, seal, and paint. Lastly, I'm fiddling with the idea of attaching a CB gasket like we do with dinghies. It might be not worth the aggravation, but there's an appeal to reducing all the turbulence in the slot. I will have to make an assessment of this. Beyond having a clean, smooth, and fair bottom and good sails, I'm wondering if anyone else has optimized their T37 in other ways. Low stretch halyards always help. I already have oversized primaries (Lewmar 52s).


 
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 Post subject: Re: A few thoughts on performance
PostPosted: 24 Nov 2020 22:52 
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Skipper

Joined: 13 Feb 2011 21:19
Posts: 270
Location: Canyon Lake, TX
Lots of good points. And they apply to cruising,too.

My navigation routing program tells me that from Boca Grande to the Dry Tortugas is 134nm. At 5knots, it takes 26 hours and 47 minutes to make the passage. Find a 1/2knot and the time reduces to 24 hours and 21 minutes. Maintain 6 knots and you arrive after 22 hours and 20 minutes.

Finding half a knot is usually as easy as trimming the sails correctly. I'm guilty of not really trimming for speed while knocking around in the bay as most destinations for me are like 2 hours away and what to do with the rest of the day?

But let the Admiral spot another boat near us and she's checking the mainsail telltales and making "suggestions".

_________________
Wayne
Master and Commander of the Sailing Vessel Impetuous
Rider of Waleli Honda 1800 VTX
Subservient to no man except SWMBO
Any day without dock lines is a GOOD day!


 
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 Post subject: Re: A few thoughts on performance
PostPosted: 24 Nov 2020 22:56 
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Skipper

Joined: 14 Jul 2012 20:36
Posts: 457
Location: Norfolk, Va
Having a solid vang is important. Losing the topping lift helps and just use main halyard when not sailing. Also the traveler needs to be upgraded. We also added another purchase to the main sheet, you really need to get on a mid-boom sheet. One Touch Lewmar winch handles are the best and is one of the only pieces of hardware we carry that top race boats use. The centerboard is so neutral it will not drop with any added resistance. Use the outboard sail tracks when off the wind, to barber haul. You really can't add hoist to the main without a penalty, to the black lines. Having a 2+2 main is nice, with the top two battens full. Adjust halyards to match winds.

_________________
Hull #208, Puff Card
Southern Chesapeake Bay


 
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 Post subject: Re: A few thoughts on performance
PostPosted: 25 Nov 2020 11:33 
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Tactictian

Joined: 06 Aug 2020 09:02
Posts: 102
I've considered a solid vang but they are pricey and I have other priorities. It just seems that with the mainsheet on a winch and the traveler properly adjusted I can exert the necessary downforce to control leech tension. If I could find a used one I might do that. I hate the boom topper.

My last mainsail of full top 2 battens and was OK but I really prefer the full batten setup for lightwind shaping and overall stability. Add to that, the full battens should extend sail life. There's some penalty for the extra weight but this is a cruising sail and the dacron is pretty heavy.

Good points about how a little bit of added speed reduced long passage times. Highly recommend the larger wheel diameter BTW. Don't be afraid to go 42" if you can find a folding.


 
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 Post subject: Re: A few thoughts on performance
PostPosted: 18 Jan 2021 22:51 
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Midshipman

Joined: 31 May 2017 22:18
Posts: 66
Location: Gulf of Mexico
OOOOHHH I'd be very interested in seeing photos of the "cascading purchase" for board control. That sounds like a nice improvement. We hadn't been messing with the board a whole lot in the first two years of ownership, but now we're starting to get it dialed and it would be even better to be able to adjust by hand without the winch.

jfalsone wrote:
While I dig deeper into all my projects, I've done enough sailing on the T37 now to have some opinions on performance. As a racing sailor, I'm always looking to wring every last once of performance out of a boat even while cruising. To that end, I've come to the conclusion that the T37 greatly benefits from a hydraulic backstay regardless of the fact that you are lucky to get 1 inch of bend from the mast. The headstay tension control and resulting control of the headsail shape make it worthwhile. I have found that I can drastically change the draft location and depth of my cross-cut foam luff roller furler this way and it is especially beneficial while close hauled. In addition, I found that while the initial stability of the T37 is not great because of the higher VCG, once heeled the boat stiffens up considerably because of the high ballast/displacement ratio. Therefore, we can hold a decent amount of sail and I am not considering a reef or reducing the headsail until upwards of 15 knots true wind while close hauled and more like 20 cracked off. I therefore had North Sails design me a new mainsail with "max roach", adding nearly 6" onto the leech in the middle of the sail. I also had them increase the hoist and went with full battens and loose foot. The added power provided by the depth in the lower third of the sail is significant. And, even with the extra area, I find that the boat still balances out quite well and I don't have excessive helm with a full main, which can be controlled with some twist (the mid-boom traveler is very effective). To maximize shaping control I added purchase to my outhaul and ran the control line back to a cam cleat in the cockpit. I also added purchase to a cunningham which is still on the mast for now. I removed the small winch for the board control line and added a cascading purchase that can now be hand-tended. This makes it easy to adjust the board on the fly and I find that the board makes a massive difference in helm feel and steering characteristics. The other thing I did recently that is really nice for driving is replace the standard Edson 36" wheel with a Lewmar folding 40" wheel. This wheel allows for much more comfortable driving positions being 2" further outboard and alse dished aft. Of course, a feather or folding prop is a must in my book. I use a MaxProp 3 blade feathering. This winter I will remove the board to conduct maintenance on the pennant, conduit, and thru-hull hose. I will take the opportunity to fair the board with templates, seal, and paint. Lastly, I'm fiddling with the idea of attaching a CB gasket like we do with dinghies. It might be not worth the aggravation, but there's an appeal to reducing all the turbulence in the slot. I will have to make an assessment of this. Beyond having a clean, smooth, and fair bottom and good sails, I'm wondering if anyone else has optimized their T37 in other ways. Low stretch halyards always help. I already have oversized primaries (Lewmar 52s).


 
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 Post subject: Re: A few thoughts on performance
PostPosted: 29 Jan 2021 10:00 
Offline
Tactictian

Joined: 06 Aug 2020 09:02
Posts: 102
sailingsoulianis wrote:
OOOOHHH I'd be very interested in seeing photos of the "cascading purchase" for board control. That sounds like a nice improvement. We hadn't been messing with the board a whole lot in the first two years of ownership, but now we're starting to get it dialed and it would be even better to be able to adjust by hand without the winch.


It's actually quite simple. My rigging is not particularly elegant because I used what was in my dinghy parts spares box so this can be improved. What I rigged was a basic 6:1 cascade (3:1 hand held purchase on a 2:1) led to a medium cam cleat. I find that this is adequate purchase without creating too much line in the boat. Having a thick line to pull on helps as does large low friction blocks. The primary cascade is some high strength line - maybe some old technora core with cover. This is plenty strong enough and won't stretch. Any covered Dyneema, say 6mm - 8mm, is totally adequate. You size this line more for wear and tear than strength actually because the loads are not extreme. Just stay with a covered line for UV protection and chafe. The trim line is probably 10 or 12 mm Dyneema core which is totally overkill on strength. Any decent single or double braid that is comfortable in your hands will do here. Loads are minimal. The 6:1 is a good match for someone of reasonable strength and is also good for holding in the cleat. My system is easy to operate but you do need to pull some if there's any side loads. I can see someone less strong wanting 8:1 BUT you can always run the line around the winch if you need to. Just be sure that you maximize the throw on the system because you will need it all between the forward cheek block and the aft turning block. See pics which show the purchase max down and max up. The geometry works just fine and beats the hell out of a dedicated winch. If it's easy to adjust, you will use it more. BTW, notice how I've set the cleat up. You must do it in a similar fashion. You need the fairlead on the deck upstream of the cleat to keep the line in the cleat under load. I also suggest a riser of some sort (angled riser not necessary, just what I had in my spares box). You will also want an extreme angle fairlead to pull from all angles while sailing. I recommend AL cleats because they are better for wear. I would add a second spring to make the closing action bulletproof. Mine is a Ronstan AL cleat that was pre-production and never produced (again, what was in my spars box). Go with the standard Harken for this application. Also, you will need to trim off the excess pennant line because it won't be needed and you don't want it flopping on the deck. My pic shows it before trimming. You also don't need or actually want a ratchet block like I have pictured. Again, just what I had in the box and the ratchet is turned off. I suppose having the ratchet might add some security but it also adds a ton of friction. As it is now, my board drops right down in a controlled manner under no load which is really nice. No need to put it around a winch!

So, here's the equipment spec:
2:1 cascade: 6-8mm Dyneema SK68 double braid
3:1 cascade: 10-12 mm single or double braid with comfortable and durable cover material
Cleat: Harken standard cam matic with double spring 150DS
Riser - standard flat riser 295
Cleat Fairlead - standard x-treme angle fairlead 375
Deck Fairlead - stainless lined for chafe protection. Ronstan PNP 122 or 123 to match line
Primary block: Single. Lots of options for blocks. Suggest on the larger size for reduced friction.
Secondary block - single with becket. Again, size larger.
Deck padeye - reuse the old one!
Fasteners - I through bolted because you don't want this cleat ripping out on you. You will need long ones and you will want backing plates because it's good practice. I think I used 3" to get through the fairlead, cleat, riser, deck, and plate. Use nylock nuts and washers.

Only downside of this system is that sometimes the blocks get a little hung up going through that combing area on the deck but it's not a real concern. Just get the leads right and don't have the purchase tangled with other halyards and lines. Again, you need to apply some force to get it up while loaded but under no load it comes right up.

Enjoyed your YouTube stuff. Wish I did what you are doing when I was young but I had other great sailing adventures of my own.


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 Post subject: Re: A few thoughts on performance
PostPosted: 30 Jan 2021 11:31 
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Skipper

Joined: 09 Aug 2017 15:35
Posts: 602
Location: Maine/USVI
Now THAT'S the beauty of this site! I've seen a cascading pennant somewhere else on here, but couldn't figure out where.


 
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 Post subject: Re: A few thoughts on performance
PostPosted: 30 Jan 2021 13:51 
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Able Bodied Seaman

Joined: 06 Sep 2020 10:08
Posts: 46
jsfalone,

Thanks for posting the description and pictures. Super helpful.

There's one piece to the puzzle I haven't figured out yet. There's a fairly narrow space through the coaming in front of the dodger (where the original centerboard pennant fairlead is). I want to run the centerboard line through there, hopefully with a version of your 6:1 together with two reefing lines. The centerboard purchase needs some width for the various parts and blocks. I haven't figured out a clean way to run the reefing lines through the same space.

The picture below shows the coaming cutaway which lines up with the space between the sliding hatch and the traveller post. From your pictures it looks like you may have run the blue reefing line around the outside of the traveller. Is that right? Do you have some extra fairleads or deck organizers in this area?

Thanks.


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 Post subject: Re: A few thoughts on performance
PostPosted: 31 Jan 2021 11:22 
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Tactictian

Joined: 06 Aug 2020 09:02
Posts: 102
madmike wrote:
jsfalone,

Thanks for posting the description and pictures. Super helpful.

There's one piece to the puzzle I haven't figured out yet. There's a fairly narrow space through the coaming in front of the dodger (where the original centerboard pennant fairlead is). I want to run the centerboard line through there, hopefully with a version of your 6:1 together with two reefing lines. The centerboard purchase needs some width for the various parts and blocks. I haven't figured out a clean way to run the reefing lines through the same space.

The picture below shows the coaming cutaway which lines up with the space between the sliding hatch and the traveller post. From your pictures it looks like you may have run the blue reefing line around the outside of the traveller. Is that right? Do you have some extra fairleads or deck organizers in this area?

Thanks.


I don't run reefing lines to the cockpit. They are in the standard location on the boom. I ran a cascade for my outhaul back to the cockpit (black line) because with a properly designed loose foot main the outhaul is actually a very useful sail control so I use it a lot. I also have my vang control line there (red line). The blue is the main halyard which is now the only one requiring a winch. I think I have a fairlead in that channel but it's mounted on the side so it doesn't interfere with the board purchase. I would suggest removing the fairlead from that spot and moving further back (is it really even necessary?). They also make much smaller fairleads now. With my design you really can't get away with the requirement for all the length required to get the necessary throw on the purchase. The way around this would be to use a single 7:1 purchase that starts right at the cheek block (max down position). This would decrease the throw but would increase friction in the system. The beauty of a cascade is less friction. I would suggest 6-8mm double braid running through some nice 40mm triple blocks. If those seem too clunky 30 might due with 6mm line. You will need a floating triple with becket up front (this is what attaches to the primary CB pennant) and a regular triple that is fixed to the deck back aft. There's a way to run the control line through the blocks to make it all fair and have it pull from the center sheave. Getting the fixed point correct is critical because you need to be able to raise the board completely. Rigging this way would mean that only the tail of the control line will be running through that channel. Just remember, larger blocks and smaller line make for less friction in the system.


 
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