mnl
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Everything posted by mnl
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I looked through a few references and most of what I found was that rake was because it looked good. As far as square rigged ships go, you can look here: https://www.cambridge.org/core/services/aop-cambridge-core/content/view/783FD78DE365F79DC6C5DA209CF6A971/S0373463323000103a.pdf/selected-issues-of-optimising-parameters-on-square-riggers-to-maximise-speed.pdf Interestingly the word rake does not appear in the document above.
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At least some people do change rake going up or down wind. A Star will have the mast raked several feet forward of vertical going downwind. You do need to be careful as shrouds and backstays start to lose geometric efficiency as the mast goes forward of vertical. I expect this has a lot to do with rake for a square rig. It makes it easier to set up shrouds. The yards require clearance to swing so the shrouds have to be somewhat behind the masts which reduces their effectiveness for athwartship support. If the mast is raked, the shrouds will be closer to ninety degrees to the mast at the attach point and provide better support.
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Mast rake is just another knob that is useful in rig tuning. Generally as the breeze comes up a little more mast rake improves things. This is especially true for a Marconi rig where it allows you to twist off the top of the main to depower the rig and reduce heel. It generally isn’t the first control you reach for as it changes other things like shroud tension. There are a lot of other variables that factor in such as the amount and location of draft in the sails. If the sail is cut with the draft forward then a little more rake may be required to bring the center of effort back to where it belongs. Another variable is the trim of the hull. If the trim is a little more down in the stern then the rake may need to be adjusted to add or reduce weather helm. A little weather helm is good, but too much is slow. You need more rudder and hence induce more drag.
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Are there better tools for drilling tiny holes?
mnl replied to Dan Poirier's topic in Modeling tools and Workshop Equipment
Find a good used Electro Mechano or Dumore drill press. You will be very satisfied. -
Making shorter straighter sections will be a big help. You will want to make a sled to hold it on the table saw. It must be clamped very securely before you try and feed it or it will go flying.
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Much better, definitely worth persevering.
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Looks to be a water color. This effect is fairly common in that medium.
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How to "unstick" this chuck from the mill spindle?
mnl replied to rlb's topic in Modeling tools and Workshop Equipment
See brinelling bearings for what happens if you use a hammer. -
How to "unstick" this chuck from the mill spindle?
mnl replied to rlb's topic in Modeling tools and Workshop Equipment
Please do not use any hammer on the top of your spindle. The bearings will not like it. You will notice there is a small gap between the top of the chuck and the spindle. They make wedges specifically to separate Jacobs tapers. http://www.jacobschuck.com/Wedge-Set/52.html -
Herreshoff New York 40 (not the more modern version)
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It looks like the stern chase guns would impede the tiller range of motion. Also one view seems to show a tiller and a wheel while the side view shows only a tiller, and one that seems to be raised for convenient use.
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Got an email from the preorder company pushing delivery back to 15-30 Sep. Don’t hold your breath.
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PM sent on Sea Ordnance.
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Renaissance Wax
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How about something completely different: New York 32: https://newyork32.org or Q Class: https://qclassyachts.com/index.html Both classes of very nice, successful racers from the 0's to the 30's, and still racing today. Lines and design rules are easily available. Best regards, --Michael
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Shamrock V displaces 146 tons. There is a rule of thumb that for a racing yacht the breaking strength of the shrouds should be equal to the displacement. A quick check of a wire rope table says 2” wire rope is 320,000 lbs, close enough. At your scale that would be 0.025”. I don’t know if they were using rod rigging yet, but that would obviously be a little smaller. I doubt they had gone to oval cross section yet to reduce windage. The pictures of Shamrock in the present day are all clearly rod rigging.
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Recomendations for a good bench top drill press
mnl replied to thibaultron's topic in Modeling tools and Workshop Equipment
The Cameron is a nice unit. There are other options from Dumore and Servo. On the used market if you can find an Electro Mechano they are very nice. -
You are within 0.001” with a pair of calipers. Have you checked it with a standard? That to me is a pretty good measurement. You need to be using a micrometer, and if you are measuring to that level of precision you need one that will read to 0.0001”, something like Brown and Sharpe, Starrett, Mitutoyo, or Elaton. Even with those measuring exactly across the flutes is hard. As far as quality goes, McMaster, MSC, Travers are all fine. Anything you get from any of them will be fine. If you are planning on drilling 316 stainless or Ti all day then selection matters. Do not buy carbide unless you have a CNC machine, you will only break them. Lastly, all drill bits flex and wander, so the hole will be larger than the drill, even if the flutes are perfectly ground. To get a minimum size hole you need to spot with starting point exactly concentric to the drill body. Most drill chucks are not concentric at that level, except maybe a small Albrecht chuck. Both the spotting drill and the drill need to be held in the appropriate collet. The feed pressure on the drill also needs to be just right so that it cuts, but does not have an excess bending moment.
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Jib Topsail downhaul / tack - running and attaching
mnl replied to juhu's topic in Masting, rigging and sails
A double block would be the most efficient way to deal with it. It would also provide the fairest run for each line. -
DHL often has much better international rates. I’m surprised more people don’t use them. If I had to ship international I would call them first.
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Question about Sails on the Yacht "Westward"
mnl replied to Ferrus Manus's topic in Masting, rigging and sails
Certainly not tactically. My impression of these boats is they mostly drag raced. Not going to have a gybing dual to try and break cover. -
Question about Sails on the Yacht "Westward"
mnl replied to Ferrus Manus's topic in Masting, rigging and sails
Probably because the staysail is used to direct flow over the luff of the main. Easier to maintain that slot relation when it sheets to the boom. It’s like a big Genoa, but for reaching. In the picture above they are far enough off the breeze it’s not really working. -
Question about Sails on the Yacht "Westward"
mnl replied to Ferrus Manus's topic in Masting, rigging and sails
The pole would never go backwards. It is generally trimmed 90 degrees to the breeze or slightly ahead of that. The pole goes from the mast to the tack of the sail. If tack of the sail is much beyond the pole it becomes harder to control. You can find another picture of Westward on a tighter reach, and that middle staysail is drawing. It is almost definitely a four sided sail. The top is set on the stay that runs from the head of the main mast to about the hounds on the foremast. The purpose of the sail is to generate flow over the luff of the main. Therefore I would expect that the head of the sail doesn’t go all the way to the foremast and the tack comes down between the two masts and potentially offset towards the weather rail. That way it wouldn’t choke off the foresail. It would then create a slot between the staysail and the main and a second slot between the foresail and the staysail. It’s all in the aerodynamics. -
Question about Sails on the Yacht "Westward"
mnl replied to Ferrus Manus's topic in Masting, rigging and sails
You don’t tack with a kite up, you gybe. If you were to try and tack you would end up with a mess. Probably the sail wrapped around the head stay, etc. The slack sail is some sort of staysail. In those days they were big believers in the more canvas the better. Hopefully they have a second pole they can set to leeward when they want to gybe. Otherwise they would have to release the headstay the inner jib is rigged on so the pole can come across. If there are two poles gibing is relatively easy. There will be two lines to each tack on the kite. In the picture above they would be flying the sail with the sheet on the starboard tack. There would also be a lazy guy attached to that tack, just hanging loose. Before the gybe the second pole is rigged to starboard with the lazy guy running through the end of the pole. When they gybe, the lazy guy is tensioned to bring the pole back to its correct position. At the same time they either let the guy through the port pole run or trip it from the end of the pole and fly the kite with what was the lazy sheet on the port side. -
The numbers being bandied about are basically the price of one Star jib. It has a competitive life of a week or two of sailing, less if it blows enough to be fun.
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