he idea of a spare mast on an HP, with well engineered masts, and zero standing rigging, seems silly to me.
Perhaps. Everyone has different views of risk mitigation. If something is extremely unlikely, do we bother?
For monohulls that can sink if a single seacock fails, or if keel bolts fail, or... or... To me, that's something worth mitigating, even if very unlikely. To most monohull sailors, it's not.
It's not that I live in fear on the water, of course. I've happily sailed many boats for years, including those that sink. But if I'm going to spend money on a boat that's intended to be days or weeks away from help, any risk mitigation is worth considering.
Then cost and convenience need to be weighed against the benefit.
When I mentioned using the boom to help lift the mast, I forgot to mention that it should be attached to the same pivot point as is used to raise the mast, NOT to the mast in it's usual location
An important detail.
These masts are not on hinges, fixed steps, or ball steps (like rotating masts). They bury 4-5' into the leeward hull in sockets with bearings.
Because of that, I'd go with Rob's suggestion of a lifting mast in a second socket right next to the main mast. It would have a block on top with a line that goes to the center of mass on the main mast, roughly 1/3 up from the bottom. Then the main mast is in "neutral" as it gets hoisted high enough to be set into the socket, with just a bit of wrestling to get it into the hole, and then gently lowered down under control.
It's possible to do it with a temporary hinge point at the bottom like on Cat2Fold, which does it brilliantly. I love how Francke thought the whole thing through, including the crank that lowers the mast.
But that really only works on a trailer. I've raised and lowered masts on the water on 20' boats and smaller, and in any sort of changing wind, or chop over 6", that puts a /lot/ of stress on whatever hinge/pin system is use on the mast foot. The boat wants to rock with the water, and without taught shrouds to it in place, the mast's momentum wants to keep it still. It's easy to bend or break the hardware.
Even on a trailer it can get dicey. Once, while raising the 36' mast on our catamaran on a trailer, we got a sideways gust of wind out of nowhere that moved the mast top about 5' away from center as we were lifting it, even though we were fighting to keep it in line. That was a very uncomfortable feeling. Thankfully it's a rotating mast on a ball step, so no harm was done. Had the bottom been hinged we might not have launched that day.
With the lifting mast, that same gust would just have weather-vaned the main mast in line with the gust. So we would have dodged the spar, kept it roughly in place with a control line, waited out the gust, lined things up again, and gotten on with our day. It still might be scary, and there are still things that could go wrong, but at least failure of a critical component would have been very unlikely.
With a 50' main mast, the lifting mast would probably need to be around 23' to have enough height be able to get the bottom clear of the deck. 17' for 1/3 the mast height, 5' for the leeward hull height, a foot to allow some clearance and maneuvering room.
So... perhaps three 8'-6" sections with 16" bury/overlap between each of the two connecting segments?
That yields a 22'-10" assembled height, giving 10" of clearance above deck if the leeward hull is 5' high.
Even in a knockdown or capsize, it is unlikely that you would lose the mast(s).
Right you are!
The most likely cause of a dismasting would probably be a flaw in the lamination that no one caught. If manufactured with good quality control, even this would be extremely unlikely.
Which is yet another reason to go with such a design.
But I'm thinking we can be more creative about ways things can go wrong. There are probably other situations in which it might be useful to be able to raise and lower the mast on your own, many miles from the trailer.
And why not get creative? It's not about fear -- since the boat hasn't been built yet, this is about how many known problems we can design away.
A few thoughts, in no planned order:
- Jammed halyard. Say your halyard jams at the mast head, you cut the line in order to avoid a capsize, and then you want to do a repair after it's calm or you beach or haul the boat. You might be able to climb the mast, but I don't know what it's like at the top of a 50' flexible mast. It might be safer or more effective to take the mast down and work on the masthead from the dinghy or a stepladder. Or disassemble the halves and see if you can safely do it on deck. You'd have to have a very calm day, or beach the boat, but you could do it.
- Jammed bearings. Perhaps the mast froze in place and no longer rotates, leaving that mast unusable for sailing. Who knows why. Salt? Sand? A material flaw? Even with jammed bearings, you might be able to lift the entire assembly free of the boat and then work on it.
- Jammed halyard or bearings. The same events, but miles from shore, and you don't want to try to remove the main mast. But you do want to sail somewhere. The lifting mast can serve as a temporary mast with smaller sail. It's not perfect, but it does offer more balance if you need to make progress to windward. Maybe it's even made of something cheap and sturdy like Tyvek, so you can keep it tucked away with plans to never actually use it.
- Masthead antennae / instrumentation. Maybe you even have to thread a whole new coax line through.
- Maintenance / inspection. My boatyard charges $100 just to touch the mast (up or down), and a few hundred dollars to haul it onto land (required before they get the mast). Even though it's often possible to have a boatyard get the mast for you, you might not want to spend that much. Or can't. Or maybe the nearest yard that can haul a multi is a long way away.
- Storm preparation. Let's say there's a hurricane coming and you've done the sensible thing of motoring way up a river (because the boats draw very little water) and have tied yourself in place with multiple lines. But what about those 50' masts? If it's a massive storm, and you're tied in place, they are a liability. Much better to take them down and lash them to the deck.
Those are things that could happen. Not once a week or once a year, but maybe once a decade.
The most convenient thing to do is not have a problem. The second most convenient thing is to have lots of spare cash on hand and then experience the problem within spitting distance of a boatyard that can haul wide multihulls and then use a crane to work with the masts.
But failures are not always convenient.
Instead of deciding whether or not the failure is likely, to me the question becomes: if the problem can be designed away for a reasonable cost/weight/convenience penalty... why would I /not/ want to do it?
A hard ridgeline for the acre of shade tarp?
Without another purpose I'm sure I would just leave a simpler, cheaper, heavier gin pole at the dock/yard/trailer.
(Comments above from Jeff previously)
Looking at the two bottom sections of the three-part lifting mast, with their narrower-diameter 16" tall portions at the top to fit into the base of the next section... those might fit nicely into some sleeves off the beams at the windward hull, or tucked into the corners where the seat area meets the cabin. That might provide around 8' of headroom at the peak under a tarp/canopy when anchored.
Maybe run two ridge lines from the posts to the masts, and tension the tarp down between them, as well as fore/aft on the outsides of the ridge lines, for a valley in a twin-peaked tarp. Now there's an acre of shade as well as a means to collect rain water.
After thinking through the details, I guess I'm sold on keeping a three-part lifting mast with me, assuming the price fits the budget.
Since it's smaller and lighter than the main masts, it might not be that bad.
- Mike
StoneTool owly@ttc-cmc.net [harryproa]
wrote on 4/11/2020 10:31 AM:
You have two masts, and two booms..... With a bit of ingenuity you should be able to figure a way to use those pieces to lift both masts. For example, with a mast laying down, the boom can be attached, and pointed straight up. A rope passed through a saddle of some sort on the end of the boom gives you the pulling angle you need to lift the mast upright. The boom is connected to the upper mast by another line so any pull on the end of the boom results in the the mast coming up as the boom tips down toward the winch. The extra boom serves as a brace to keep the mast from tipping inboard or outboard as it comes up. The first mast can then lift the second a good share of the way up using a halyard. Figure it all out at home obviously, and rig the necessary hardware and attachment points, and any other special stuff you need.
The idea of a spare mast on an HP, with well engineered masts, and zero standing rigging, seems silly to me. Being dismasted is a very remote possibility. You have eliminated ALL the dozens of failure points on conventional boats by dispensing with the absurd tall spindly mast that has to be held up by a complex spiderweb of rigging, the failure of almost any component of which will send the mast over the side. You have a fundamentally strong mast, not a fundamentally weak one. It always amazes me that so many people can't see the obvious... that a single critical point (the point where the mast projects from the partner), is less likely to cause a dismasting, than 50 or 60 components, the failure of any of which is critical!! My math says that you have 1/50th the probability of failure. An extremely sudden and powerful gust with too much sail up, might fail the the mast, but that is an extremely unlikely event, and the guy with a stayed mast will fail first.... a cable swage end, a stainless fitting, a chainplate, etc.... Even in a knockdown or capsize, it is unlikely that you would lose the mast(s). You have far less hitting the water than a conventional design has.
Howard
On 4/10/20 12:24 PM, Mike Crawford mcrawf@nuomo.com [harryproa] wrote:
While interesting, it seems a bit much. Not only a spare mast, but two spare masts? Of course you'd be elated to have them if ever needed, but has any sailor ever gone to sea with 4 masts for a smallish boat?
I can't argue with you.
There's also a case to be made for a single spare mast that's also a lifting mast. It's less weight and cost, and it still lets you remove/install masts if you're in the middle of nowhere, perhaps if one breaks. And then it's a spare that can take over for the mast that got replaced. It would probably have to be a two-part mast anyway, to be tall enough to be useful while still fitting between the mast bulkheads and/or allowing it to be removed from the hull.
You couldn't lose both of the primary masts and then keep going, but perhaps that's going overboard. That's more of a thought experiment on how safe and redundant one can get.
A hard ridgeline for the acre of shade tarp?
There's a thought.
My plan was to run a fixed line between the two masts, then run a second line from the center of the first, down to the deck on the lw hull, and then tension it with a simple dingy block/cleat. Then three lines running from the ww hull -- one to each mast, and then one down to the center of the tensioned line. If you run a canopy from the ww hull to the lw hull, the sides would be the high points, and water would drain down the center. Also a good way to collect rainwater.
But that would require some sort of structure on the windward hull, wouldn't it? My original plan was to go with the retractable hard top on the Mark I Ex40, but I'm sold on the new version with the fixed cabin top. Which means now I'll need some posts for that canopy.
Simplest-and-lightest might be a three-part mast, with two sections that fit into sockets on the windward hull. Though they'd almost certainly be overkill in terms of weight and strength. Or maybe not -- they'd be under a lot of stress once the lines that support the canopy are tensioned.
Shelter-wise it might be nice to have a ridge line with lower sides instead of a butterfly ridge, though that would make things a tad more complicated.
Hmm. I never really thought through the tarp-while-on-the-hook plan.
A trebuchet to keep the pirates at bay?
Arrr!
There aren't many ways to deal with pirates that will also clear customs at each new country/anchorage, are there?
Without another purpose I'm sure I would just leave a simpler, cheaper, heavier gin pole at the dock/yard/trailer.
Once the decision has been made to go with a weight-to-windward proa with an unstayed schooner rig, many of the other safety considerations are secondary. A spare mast? How many? We're splitting hairs at that point, particularly because it doesn't change the boat design.
I wouldn't spend $10,000 - $20,000 on spares, but I would spend a few thousand dollars. If it's a simple two-part or three-part round tube, that might be possible. It's tough to say. Without a project or budget, all of it can be justified. Then later, when the project inevitably starts exceeding funds available, those carbon fiber spares masts are going to be the first things to go.
At which point it would be time for something heavier and simpler like fiberglass or aluminum, left ashore after the masts are up.
Now the boat is even lighter and cheaper.
Not nitpicking, the rest of the post is gold
Nitpicking is a good thing as long as the boat isn't built yet! It's always useful to have a reality check before making the leap.
Though it's nice of you to be friendly about it. That makes it easier to work on improving ideas rather than on trying to defend them.
- Mike
Jeff Royster jeffroyster@gmail.com [harryproa] wrote on 4/10/2020 12:55 PM:
"Emergencies. You could carry two short masts in the hull space between the beams, which could also double as lifting masts to hoist the primary masts into place."
While interesting, it seems a bit much. Not only a spare mast, but two spare masts? Of course you'd be elated to have them if ever needed, but has any sailor ever gone to sea with 4 masts for a smallish boat?
I think I'd have a hard time building, paying for, and hauling spare masts just in case. Perhaps if they could serve some other purpose too? A hard ridgeline for the acre of shade tarp? Posts for cockpit shade? A crow's nest or tuna tower on the WW hull? A trebuchet to keep the pirates at bay?
Without another purpose I'm sure I would just leave a simpler, cheaper, heavier gin pole at the dock/yard/trailer.
(Not nitpicing, the rest of the post is gold)
On Wed, Apr 1, 2020, 7:11 PM Mike Crawford mcrawf@nuomo.com [harryproa] <harryproa@yahoogroups.com.au> wrote:
Erutan,
We had a brief discussion on schooner-vs-telescoping rigs a while back, which I'm including after my signature now that we lack the web interface or history.
Which came to mind as I was reading commentary in Practical sailor about AIS signals not working when the VHF is transmitting.
On the boat in question there were two antennas, and the owner reported that sometimes other boats would drop off their AIS display when using the VHF, and had friends report that the the owner's boat would drop off their displays. The author instead recommended a splitter and a single antenna, which still stops receiving and transmitting AIS when the VHF is sending, but otherwise will work.
Unless... you can mount the antennas more than 2 meters apart!
So, as long as you have an HP schooner rig with fixed masts, or some way to limit rotation so the VHF cables don't twist, you can have both VHF and AIS at the same time. Pretty cool.
Another reason for me to consider the simplicity of the schooner..
- Mike
<<Perhaps Robs telescoping masts make sense, as the masts can fit on the trailer. Also the shorter mast is perhaps easier to wield.>>
Erutan,
You've zeroed-in on the largest remaining question about what I would choose.
SCHOONER RIG
Being the conservative kind of guy that I am, I'm currently in the schooner rig camp for the following reasons:
- Steering. You can steer and shunt the boat with the schooner rig even if both rudders are taken out. You could even beach the boat, fix it, and launch it back through (calm) surf without rudders, and then sail it home. Depending upon skill and weather.
- Emergencies. You could carry two short masts in the hull space between the beams, which could also double as lifting masts to hoist the primary masts into place. So you could: a) have two emergency masts on-hand, if you need them for some reason, and b) you could beach the boat and remove the masts for work with just one or two people. The emergency masts would be slow, but they'd at least be present. Or maybe fasten the short masts to the beams themselves if it's too hard to find a way to get them in and out of the hull. Or just make the emergency masts in four sections each and assemble them when needed.
- Accommodations. That space between the masts could also house one or two pipe berths and/or a second head. Or at least a compositing toilet with a curtain. A great place for the kids to stay up late and talk too loud about boys, girls, or Call of Duty.
- Stresses 1. Putting the masts right next to the beams lets you build a much stronger boat with much less material -- handling torsion over the distance between a central mast and outboard beams is not trivial, particularly if you want to incorporate one or more openings.
- Stresses 2. While the total heeling moment won't change, each mast would only be applying half of the total force to the boat, and would be putting that force much closer to the beam that resists it.
- Sail area. You can put up a honkin' amount of sail area while still fitting under the ICW bridges and/or staying within trailer limits. With a lower COE than a single rig.
- Shipping. Twin 46' upper masts (stub mast in the lw hull) would easily fit into a 48' high-cube shipping container. Maybe 50' masts in an extra-long 52' container -- because an EX48 maxiTrailer would need a container larger than 48' unless the lw hull bows are removable. Assuming the ww hull fits into the high-cube dimensions, which is probably the real limiting factor.
- Shade. How cool would it be to string up some dyneema lines from the cabin roof to the two masts and run a tarp between then while at anchor? A half-acre of shaded deck/tramp space.
- Simplicity. You'll never have to worry a about a non-telescoping mast jamming in the up position during a storm. There's also no joint to deal with when figuring out how to get a bolt rope, mast track, or mast hoops to transition from the lower section to the higher section.
- Righting. It's possible, in theory, to right a weight-to-windward proa in a knockdown, depending upon the sea state. Sealed unarig masts would offer more stability and flotation than a single telescoping rig.
TELESCOPING RIG
Yet despite all those reasons, the convenience of a single mast still calls.
- Sail area up high. Okay, I just said that I like having a lower center-of-effort with a schooner rig. Which is true when the wind picks up. But when the wind is really light, there's more of it the higher you go, and a super-tall mast is a great way to consistently move across the water with wind in your face on days when a normal rig might leave you just sitting still.
- Single mast for shunting. It's possible that with deep enough rudders, the right hull rocker, and backwinding the "jib", a schooner rig will tack. Or not. In which case shunting a single taller telescoping rig takes half the effort of shunting a pair of shorter rigs.
- Sail area at anchor and in storms. A single retracted telescoping mast will probably present less of a heeling moment under bare poles than the pair of fixed masts on a schooner rig.
---
Basically, since I want to eventually go places in the boat, the schooner rig is really the only option that fits my safety criteria.
But because it's about five miles out to open water for me, through an inlet that ranges from 1/4 to 1/2 mile wide, the telescoping rig still calls to me. That's a lot of short-tacking today in the catamara, and wold be a lot of short-shunting in a proa.
The good news is that with the proa I'd never have to worry about blowing a tack too close to shore and then heading into the rocks.
But the thought of shunting one sail instead of two is still attractive. I can see why someone else would choose it.
__._,_.___
Posted by: Mike Crawford <mcrawf@nuomo.com>
| Reply via web post | • | Reply to sender | • | Reply to group | • | Start a new topic | • | Messages in this topic (8) |
.