Design Spiral into Madness

Discussion in 'Multihulls' started by Owly, Apr 15, 2021.

  1. Owly
    Joined: Oct 2016
    Posts: 139
    Likes: 12, Points: 18, Legacy Rep: 10
    Location: Montana USA

    Owly Senior Member

    I'm not exactly looking to solve any "problem" specifically. Looking at available catamarans, the most abundant and readily available in a price range that makes sense to me are the Wharrams. There is as much to dislike about them as to like about them. The flexible beam structure creates problems if you want an integrated bridge deck cabin, and that leads to the idea of the half cabin integrated into one hull, which becomes a problem if it becomes very large. The idea of a bridge deck cabin of course is to allow a sheltered watch keeping & lounging position out of the weather with a good view, easy deck / cockpit access, and dry access to the hull with the galley and head, etc. Then there is the issue of fore and aft access. A rigid cat with a full cabin makes forward access from the cockpit a pain.... if it is not a big boat where you can simply walk through. The half cabin retains the clear and protected walkway fore and aft with a hull forming a barrier between you and the "deep blue". That is all well and good. I fundamentally dislike standing rigging, and in that I seem to be the minority. Where some people see a sturdy well braced mast, I see dozens of components, any of which if it fails will bring the entire works down........ a house of cards made worse by crevice corrosion, and of course leaking chainplates / rot, etc. Free standing masts become less practical the taller they are, so logic dictates two shorter free standing masts rather than a single very tall stayed mast. That in turn points to a more rectangular sail to maximize the sail area.... increasing it as it must be carried lower and in a lower wind gradient...... The junk rig makes sense to me because it not only provides this, but does it while eliminating numerous pieces of troublesome hardware, as well as providing sail balance area, and instant reefing on virtually any point of sail, and it completely eliminates headsails, and of course being rigged on unstayed masts, the sails can be set right across the wind, which is pretty ideal for tradewind passages. You have no sail track, no traveler, no vang, no furling gear, no need for winches, preventers, etc. Ok.... So far we have a half cabin functioning as a pilot house on a Wharram flying a biplane junk rig. So then comes the bidirectional aspect... making strange even stranger. Two rudders are used fore and aft alongside the hull like the Harry Proa.......But it isn't a proa strictly speaking because it is intended to either tack or shunt, probably tack in most cases. The cabin may be placed on the windward side for shelter, or on the leeward side for a cooling breeze, or simply on the side to block the sun and provide shade........Or whatever you want. To make it all balance out properly for bidirectional sailing, the masts need to either be centered, or offset equally. Offsetting them fore and aft may be the desired solution in the narrow confines of a catamaran hull, and of course the diagonal offset follows from that.
    The "benefit" of bidirectional sailing is debatable at best........ I really have not found a strong case for that, though there are a few convenience aspects. It's more just a look at how a unique and different configuration could work..... a proverbial "solution in search of a problem" as they say. But napkin sketches and mental gymnastics cost nothing, and are probably a better occupation of time than watching TV...... (note that at 65, I've NEVER had one of those infernal contraptions & don't see one in my future).
  2. Rumars
    Joined: Mar 2013
    Posts: 1,078
    Likes: 467, Points: 83, Legacy Rep: 39
    Location: Germany

    Rumars Senior Member

    You're funny Owly, no doubt about it. You don't like a mast held up with string, but you're willing to use it to keep the hulls togheter. By the way, standing rigging does not have to be made out of many liitle pieces of corrosion prone stainless.
    I don't know what size boat you imagine, but there's no shelter problem a bridge deck with a hard dodger can't solve for you. If the boat is to small for that, well, a proa style side cabin will not offer more protection then the equivalent hull cabin or central cuddy.
  3. redreuben
    Joined: Jan 2009
    Posts: 1,771
    Likes: 114, Points: 63, Legacy Rep: 349
    Location: South Lake Western Australia

    redreuben redreuben

    Most of your argument against standing rigging can be resolved with composite fittings and textile rigging.
    Freestanding masts parked at each end of a Wharram hull is a recipe for massive pitching and hobbyhorsing.
    Freestanding masts already have extra weight plus the hull reinforcement to keep them up all moved out away from centre of rotation ? Nup.
    Further with the masts in each hull you have sail control issues when the leeward sail is out over the water.
    Junk rig, don’t know much about them, never even seen one. But from reading while they seem easy to use and simple to maintain one feature keeps coming through, slow. Which means more food more water and more slow.
    For a cruising boat I like the idea of a wishbone boom on a sloop rig.
    Accommodation, for hulls up to 10 metres l rather like Woods big mast beam and pod cabin solution for 2 reasons that work for each other, access forward and privacy.
  4. Owly
    Joined: Oct 2016
    Posts: 139
    Likes: 12, Points: 18, Legacy Rep: 10
    Location: Montana USA

    Owly Senior Member


    Let's address these things one at a time........
    There is no doubt that synthetic rigging can improve the situation with standing rigging, but there are still dozens of components any one of which if it fails can result in a dismasting.......... not at all uncommon. The result is a typical 10 year 100% replacement cycle. There are very large compression loads from a stayed mast because the rigging is trying to push the mast through the bottom of the boat... or the deck. There are also considerable forces on the chainplates, and chainplates are a maintenance and leakage issue. You grossly over estimate the forces on a free standing mast. With proper bury the loads are easy to deal with, and no they typically are not all that heavy. You also eliminate ALL standing rigging components winches, and various other hardware, so in the end there is typically little net gain in weight, and a lot of reduction in windage and of course maintenance. Such well known designers as Eric Sponberg have much good to say about them. There has been much discussion on the topic, no point in re-litigating the topic here.
    No I don't advocate placing two masts at the extreme ends of the hull. You will note that on the orignal Wharrams, the mast is not in the center, but typically forward of the main cabin more or less. The purpose of diagonally opposite masts is to have one mast the same distance aft of center as the other is forward..... that doesn't mean a double catboat ;-) Note that I called it a biplane schooner, not a biplane catboat.
    Your comment about difficulty in controlling the outboard sail shows an ignorance of junk rigs..... it is no problem at all because sail camber is built into each panel and does not depend on vangs, travelers, and winches....... You just let the sheet out to where you want the sail and cleat it off.
    "Slow" is a relative term, and in reality junk rigs do not win races because they don't sail as well to windward, but from a beam reach aft they tend to equal and then outperform a Bermuda rig as they reach the downwind points of sail......... That of course assumes a modern camber panel junk of equal area on a similar boat. The reputation of "slow" is one that will never be shaken once earned, and it was earned by the old flat panel junks. Blondie Hassler's Jester (Nordic Folkboat flat panel junk rig)came in second to Chichesters Gypsy Moth, a far larger boat in the first Ostar, and Blondie sailed the race in bedroom slippers and never left the cabin.... there was no cockpit. His sailing was done through a hatch in the deck.
    Here is a comparison (race) between two identical boats that is worth reading and puts performance into perspective. The junk lost so that should give you some satisfaction ;-) Bermudan rig vs Junk rig - Practical Boat Owner
    Last edited: Apr 18, 2021
  5. Owly
    Joined: Oct 2016
    Posts: 139
    Likes: 12, Points: 18, Legacy Rep: 10
    Location: Montana USA

    Owly Senior Member

    This is a "mental exercise", not something I really proposed to do.... Something fun to toss around that is far from conventional. I chose Wharram's as the platform because they are readily available / plentiful. There a number of aspects of Wharrams I am not fond of, the top of the list would be the canoe sterns, and close behind, the lashed or otherwise flexible construction, which surprisingly has proven to be reliable....... but so have rigid beams. The fact that they are essentially double enders leads to bidirectional potential, it otherwise is a pure liability IMHO. It reputedly makes them prone to hobbyhorsing, (I believe there are solutions to this) and obviously makes them longer for the available space in the hulls. Richard Woods who once worked with James Wharram and has designed many excellent boats has no designs with either of these features....for good reason. James is a great sailsman (typo intended), but anything but progressive. His boats seem to all be variants of one design. He's a prophet who has surrounded himself with acolytes who revere him, and who are still building his designs.

    I have my own ideas about how I would design a catamaran if I were willing to undertake such a project, and there would be almost no resemblance to a Wharram. It would have dory hulls most of it's length except the bow area, It would have shallow LAR keels for grounding as much as for leeway, and perhaps daggerboards as well. it would have transom sterns... if they had steps at all, they would angle inboard about 45 deg. It would have a full bridge deck cabin that was less than standing height because the boat would only be about 30-34' long. It would have a "pop top" like the FP Maldives so you could have standing height and ventilation in good weather, or 2 or 3 sliders conveniently located, (the simpler more reliable solution) but I consider "galley up" absurd in a boat that size. It would have abundant bridge deck clearance. It would have a boarding ramp on one end much like they frequently use on Wharrams. Windows would be designed to avoid the greenhouse effect........ I hate those streamlined windows often seen on cats... nothing about them looks good to me except styling. The berths would be aft, and have generous "wings" extending into the cockpit area. It would NOT have an inboard, though I'm very comfortable with diesels, having rebuilt dozens of them over the years... I don't want an engine in a hole dragging a prop through the water, and generally creating a stink and a mess below decks.

    When you are doing "napkin designs", there is really no reason not to play with unconventional approaches. As a kid building model airplanes, I was laughed at when I built a model with a an engine on the fuselage and another on one wing like a regular twin, but 50+ years later Burt Rutan built Boomerang. Because it "isn't done" doesn't mean that it won't work or has no merit. Our natural inclination is that if something doesn't look conventional, it must be wrong. We look at things through a lens of conventional thinking. Oom Paul Kruger has a brief audience with Joshua Slocum, and ended it in a huff after Joshua claimed to be sailing "arround the world", rather than across a flat earth as Kruger believed it to be. Look at Rob Denny's Harry Proa designs.... they just look wrong.... One hull longer than the other with one or two masts on it, a short fat hull with a cabin one one side, flat bottom, no daggerboards or keels, rudders between the hulls well away from the ends.... is it a Pacific or an Atlantic Proa.... Masts on the lee hull make it Pacific, most of the weight on the windward hull make it stable and capsize resistant. It just looks wrong, but when you examine it in detail with an open mind, you will find a LOT that is right about it. Of course Rob is actually building and sailing full size boats, not just doing napkin sketches and daydreaming. He's well past that stage of the game.

    In the "napkin stage", you can sail the seas of your dreams, imagining what it will be like to sail your imaginary creation.... If you have the ability to do that. If you find something that just doesn't work..... It may be the labor of an hour or two of daydreaming to find the solution, and resume your sailing. How do you like that nice stretch of open deck connecting the fore and aft ends protected by the cabin and one hull.... Will you use it as a center cockpit? When will you choose to sail with the cabin to windward, and when to lee? and why? Shade, wind protection or cooling breeze. The galley and head are accessible from the bridge deck cabin without stepping out. It is not a doesn't care which side is to windward..... but it can shunt. In some situations you may choose to shunt rather than tack. You sail off anchor or mooring, etc without reversing. It has some of the features of an open deck cat, some of a bridge deck cabin cat. For a solo sailor, you would live in the cabin and integrated hull mostly. The other being stowage, and perhaps a guest cabin(s). Are their advantages? Are their disadvantages? The answer would be yes to both, and how we balance those depends on the man and his priorities.

  6. guzzis3
    Joined: Nov 2009
    Posts: 532
    Likes: 56, Points: 28, Legacy Rep: 42
    Location: Brisbane

    guzzis3 Senior Member

    Are you talking building or buying second hand ?

    Wharrams have next to no resale value so I guess they make a good testbed, but you always have to remember to compare them by waterline length not LOA. A Tiki 38 for example is a 31' cat with extra weight and cost in the overhangs.

    You would be out of your mind to build one. A Woods cat same waterline plans will be comparable or cheaper and the boat will be easier and cheaper to build and it will be worth something when finished. It will also sail better.

    Sounds to me like you need a harryproa. Unstayed carbon masts, boards that double as rudders, clever accommodation....

    Junks have some specific advantages but sailing to windward is always the hardest point of sail. On any boat pretty much that should be your primary concern.

    You can eliminate that on a marconi. I'm obviously wrong because no one else rigs a boat like I do, well not many anyway. Ian Farrier took up the double mainsheet on his tris as an alternative to travelers. I call them bridle mainsheets but I've seen them refered to as DMs...I don't run vangs usually although you probably need a downhaul of some sort. I like a furler on a screacher but prefer a hanked jib. It's unusual but you can fly a triangular loose all round.

    However you seem to have missed the really big opportunity. Crabclaws, well designed, have been shown to be tremendous on all points of sail including close hauled. Marconis outperform then just while pointing really high, but as you come off the wind they eat everything else pretty much.

    And they look the business! :D

    Rather than waste your life flogging a dead Wharram I reckon you should get some plans from Rob and build a Harry. Great fun :D
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.