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Hi all,
I've just acquired a new-to-me 1985 C&C27 Mk V ('Aurora' out of Outer Harbour Marina Toronto). Since this is my first 'real' sailboat I'll likely be here quite a bit.
Several questions:
Are there specs for shroud tension rig tuning available?
Cunningham? Saw the rigging diagrams - couldn't find it. My boat doesn't seem to have one rigged - what's the set-up for this? Is it lead back to cockpit? at the mast?
The deck near the anchor locker locking bolt is a little wet on the moisture meter (a common problem or so I've heard). No extensive damage but is there a way for me to stop it from getting worse?
My sails are all 1997, 1995 vintage and a 1985 spinnaker which looks like it's never been used. This is a tough question to answer sight unseen, but how much life can I expect out of these for pottering around the lake? Anyone have any used sails for sale, or know roughly what it costs for a new suit?
Other issues from the survey: Engine RPM guage is dodgy - is this common to the boat or likely some old wiring?
I'll probably have tons more questions. thanks in advance for your advice. Any tips and pointers much appreciated.
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Last edited by (2004-10-19 01:37:48)
Hi
I don't know of shroud tuning tensions for the boat, but check out the tuning guide found under the MKV link on this homepage.
I rig my cunningham with a 4 part purchase & v cleat at the mast.
Deck repair - search the web, try black arts on this web site, buy a book. The sooner you fix it the better.
My boat came with main, #1,2,Jib & spinnaker - all 1985. The dacron main & gennys are fine for cruising, but way too old for racing. My 1985 spinnaker was little used and still is fine for racing.
New Quantum sails: Dacron Main $2800; Kevlar #1 $2800, #2 $2700. The boat is so fast in over 18 knots I'll never buy a #3, the old one is just fine.
Enjoy the boat, race fast.
Jim
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Decks usually get wet because fittings are loose or the bedding compound is compromised in some way. The best way to fix the problem is to put a good tarp over the boat for the winter, then remove the fittings in the damp area. Clean off any remaining bedding compound with varsol or similar and leave the boat to dry over the winter (I know it gets damp by the lake over the winter, but overall, this will reduce the dampness in the laminate).
Come spring, re-do all the mounting holes with the "drill, fill, drill" process described in Black Arts. You'll have to modify the process a bit -- you've already got holes right through the deck, so you'll have to find a tape or some sort of plug that won't let epoxy run through, but by doing this, you'll ensure that there will be no repetition of the wetness. Re-bed your fittings and you're done. (This sounds a lot more complicated than it is.)
As to your cunningham, where you lead it depends on what you're going to do with the boat. If you short-hand, you'll want it led aft, or it never will be used. If you race with a full crew, you'll want to lead it to wherever the person charged with the main trim will be posted.
If you have any sort of engine or electrical issues, I suggest you call JLC Marine. He sorted out my engine and its electrics and it has never run better.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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Re: shroud tension. My MkV is also a 1985, hull #75. I've been playing with the shroud tension for a couple of years. I use a "Loos gauge" Model B for measuring the tension. The upper and lower shrouds are 7/32" 1x19 wire and the mid shrouds are 3/16" 1x19 wire. The rated breaking strength for 7/32" is 6300 lbs and for 3/16 is 4700 lbs. It is not recommended to exceed 25% of rated breaking strength for the wire for the initial static load. But this allows a lot of tension. I have found about 1000 lbs for the upper and lower shrouds is about idea. This is about "34" on the Loos gauge. I usually give the mid shrouds about 500 lbs, which is about "24" on the Loos gauge. Even at these seemingly high levels of tension, the leeward shrouds will go a little slack when close hauled on a really windy day. Slack shrouds are more of a danger of failing than tight shrouds due to the potential for shock loads when the shrouds are slack.
I ended up going a bit tighter with the upper/lower shrouds, to prevent them from going slack so early:
- 1210 on uppers
- 1085 on lowers
- looser in the middle ones - can't remember the setting.
This seemed to give good tension under reasonable wind conditions.
I find the RPM gauge unreliable as well, but under most conditions it doesn't really matter as you don't get much speed increase past 2K, so I don't run it much higher than that.
Getting some bend in the mast, without tensioning the forestay on the other hand seems to be more tricky. The only way I seem to be able to do it is to tighten up on the baby stay, and then take up on the backstay. Masts with different shroud arrangements seem to make this more feasible. Anybody else know how to do this, or is it just not such a big deal on this boat?
Hi John,
Baby-stays are used to replace lower/forward shrouds to improve sail trim, Namely, you can bring the jib in tighter if there is no forward shroud and point better. The lower shrouds are normally tensioned so as to supply pre-bend to the mast when used in co-ordination with upper shroud tension and back-stay tension. So it's reasonable that adjusting the baby-stay will also adjust the pre-bend, which isn't really pre-bend any more since you adjust it on the fly, pulling the middle of the mast forward when you want it, slacking off when you don't. The amount of rake set for the mast will also affect the contribution of each adjustment for your boat. How you use it is, of course, up to you but, basically, you're doing the right thing with your set-up.
Gord
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The other thing the baby stay does is to reduce "pumping" of the mast fore & aft when going upwind in a chop. We tighten our baby stay up in wavy conditions - but we don't overdo it. First, the angle of the baby stay up the mast is so sharp on a MK V that you can't really do much with it. Second, the chainplate leads to the forward bulkhead - and if you look at the bottom of the forward bulkhaed on a MKV you will see it is anchorded to...nothing! So we use medium tension, and rely on the backstay to bend the mast - which it does just fine.
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Re: tachometer flaky. Mine is too! This doesn't sound like a coincidence. When the tach works, it is accurate as far as I can tell. When it doesn't work the symptom is very slow response to changes in engine RPM. If I stay at a steady RPM long enough, the tach will eventually read correctly. But any change may take many minutes to be reflected. Even after shuting off the engine, the tach takes several minutes to fall back to zero. I suspect a bad resister or capacitor or cold solder joint in the "damping circuit" on the tach. I have not been able to detect any pattern to tell under what conditions the tach works or doesn't work. Has anyone had any experience fixing this problem?
Re: engine RPM vs. boat speed. There are a lot of variables that effect this, such as the prop size, boat loading, engine and fuel condition, bottom growth, etc. There has been a raging discussion about this on the "Sailboat Owner's" Web site for years. Yanmar recommends that the engine be run at at least 3200 RPM at least occasionally. The engine may require more maintenance if run at too low an RPM for too long. The engine power and fuel efficiency graphs in the Yanmar shop manual show 2900 RPM as the optimal operating speed for this engine. If the engine cannot reach 3600 RPM in gear and under load, then there is something technically "wrong" with the set up. Usually, this is an over-proped condition. The engine is rated to run at 3600 RPM for up to one hour and 3400 RPM indefinitely. Experts say that a sailboat owner is an diesel's worst enemy, since we don't use them enough or run them hard enough.
With regard to no speed increase over 2000 RPM, I do not find that to be a problem with my boat. I have a 2-blade folding prop, the C&C recommended 13" D x 8" pitch RH prop. Careful speed measurments with GPS, replicated at least three times at each RPM and run on 180d courses, show the following averaged results for my boat:
800 RPM = 1.67 Kt
1000 RPM = 2.10 Kt
1200 RPM = 2.67 Kt
1500 RPM = 3.13 kt
1700 RPM = 3.75 Kt
1800 RPM = 3.95 Kt
2000 RPM = 4.40 Kt
2250 RPM = 4.95 Kt
2400 RPM = 5.15 Kt
2500 RPM = 5.43 Kt
2600 RPM = 5.60 Kt
2700 RPM = 5.85 Kt
2800 RPM = 5.80 Kt
2900 RPM = 6.00 Kt
3000 RPM = 6.20 Kt
3100 RPM = 6.38 Kt
3200 RPM = 6.38 Kt
If you fit a linear regression line to these data, the resulting equation is Spd(Kt) = 2.1 * RPM/1000
Boat speed continues to increase steadily up to 3100 RPM, after which there is no gain. This is above the theoretical hull speed of the boat anyway. This also indicates that my boat is either overloaded or slightly overproped, since the maximum RPM it could reach was 3200. According to "experts" each inch of diameter or pitch increase on the prop takes 250 RPM off the engine top speed.
One last thing: I had a friend with a Hunter 31 who was paranoid about his Yanmar diesel and never allowed it to go over 2200 RPM; he had nothing but trouble with that engine. My theory with diesels in boats is the harder you work them the better. Just give them clean fuel and proper oil changes.
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