505 type dinghy as a cruiser

Discussion in 'Sailboats' started by milessmiles, Oct 3, 2013.

  1. milessmiles
    Joined: Oct 2013
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    milessmiles Junior Member

    Hi, a friend is giving me a prototype 505 style dinghy. It should really be sailed two handed and trapeezed. I want to sail it single handed or with inexperienced crew without going swimming. If I build a centreboard and attach a lead torpedo shape hung on wires would this help stability. What weight would the torpedo need to be? Would a longer metal centreboard be an idea, or would that just reinforce heeling at the point of capsize. Any ideas to help stabilize the boat would be very welcome.
  2. sawmaster
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    sawmaster Senior Member

    re:cruiser from 505

    you cant really make a cruiser from that type of high performance racing dinghy-if you mean a vessel with a cabin,sleeping arrangements, marine toilet,etc -used for coastal voyaging or trans-oceanic passages-that is the usual definition of a cruiser.Sounds to me you're really looking to de tune this racing machine and turn it into a daysailer.If so, I would recommend changing the rig, instead of the centerboard.First, do away with the jib and the spinnaker,then try to find a mainsail with about a third less area than than the current main,one that doesnt go all the way to the top of the mast.Try to find one with the center of area slightly forward of the current main sail to avoid "weather helm" which is caused by the center of area being too far aft of the center of lateral resistance and results in having to sail with the tiller always a little to windward of the centerline causing your rudder to act a little like a brake(although if not extreme, might not be too bad since you really dont want be going real fast anyway)A shorter sail of less area will make the boat less "tippy" and should do away with the need for experienced crew/trapeezing.
  3. wet feet
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    wet feet Senior Member

    The wrong boat for the purpose.Adding a chunk of ballast would make it more difficult to handle ashore and will be fairly ineffective in use.A smaller rig would be a sound idea,but really the original poster should seek a more suitable boat for cruising as it would take a lot of time and effort to adapt a 505 for a role that doesn't suit it.
  4. Richard Woods
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    Richard Woods Woods Designs

    I agree with the other posters. If only because you have to launch and retrieve the boat and a 5-0 is heavy enough for one as it is. Never mind one with an added weighted keel - which will anyway only really help at extreme heel angles. So it won't stop you capsizing

    Richard Woods
  5. messabout
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    messabout Senior Member

    A few years back I converted a Thistle to a beach cruiser, used mostly as a singlehander. It had a monorig of much reduced size along with a small outboard. It sailed well and putted along nicely with the outboard. It was roomy and simple to sail. Of course it did not go as fast as it would with the conventional rig. No cabin or cover was used but it made an exceptionally gratifying beach cruiser.

    The Thistle is a little bigger than the 505 but the five-o would make a decent picnic or family outing boat with a smaller rig. The boat is not suited for anything like a cabin. It will not need any ballast if the rig is kept very conservative. It is also not suited for heavy loading. It is a two handed boat and designed to operate with somewhere around 400 pounds of crew weight or less. In its standard form it is a very able performer. Its' intended purpose is racing and it demands some skill when rigged according to class standards.
    Last edited: Oct 3, 2013
  6. milessmiles
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    milessmiles Junior Member

    Thanks for your replys, its a free plastic hull and alluminium mast, an early stage of a friends project, about 90 kg. Small self tacking self furling jib, I assume I can put a standard mainsail on and heavily reef it. Whilst I'm relatively new to sailing I have crewed and helmed a 505 under excellent instruction and have use of other boats. The crew will sometimes be nearly blind, crippled with arthritis, captain slow or myself single handed. Will launch off sandy beach into river.
  7. SteveMellet
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    SteveMellet Senior Member

    This topic interests me as I too have an old 505 hull waiting to have something done to it. Mine was originally unsuccessfully turned into a skiff with huge racks, a 26ft keelboat rig, with a 14ft dighy mast as a bowsprit ! It has also been modified to have a daggerboard rather than the centreboard.
    I have the hull and racks, have removed the old rotten deck and have an open hull to do something with.
    I've thought of turning it into a milder daysailer with two masts with a rig setup like the Core Sound boats, ie two simple freestanding laser style mains, no jib. Perhaps have a bowsprit and an assymetric spinnaker, for use in under 15knots. No trapeze, just hiking. I figure it could carry 3 adults, maybe 4 as we are mostly lightly built (would have to choose my crew) :D.
    I've also drawn up a cabin for it which would be small, as storage or for one adult or 2 kids to sleep in.
    I've also considered getting two beachcat hulls (not Hobie) to turn it into a trimaran, which is actually my most preferred option, for many reasons.
  8. gggGuest
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    gggGuest ...

    The thing you always have to consider is displacement. The boat is't really going to work well with very much more weight than it was designed for.
  9. SteveMellet
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    SteveMellet Senior Member

    One of the main reasons I would consider the trimaran option over adding ballast. Both ways the boat gets heavier, but adding amas means adding bouyancy, not ballast. If the ama volume is enough, the boat should be able to carry more people than the single hull would, and there would be more space for them to spread out in lighter breeze. I've seen the Weta tri carry 2 adults and 2 kids, this would be like a scaled up version, so the same or slightly higher crew weight should be no problem.
  10. milessmiles
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    milessmiles Junior Member

    My ballast torpedo idea is to counteract not having a trapeezing crew member or no crew. Crew will be moving to balance boat, best they can, I can still hike/trapeeze with a helm extension to move my weight.
    Another idea I have instead of trimaran is to have a board accross the middle of the boat, overhanging 50cm? each side for the one crew membet to sit out on as a substitute to trapeezing. Under the overhanging board sufficient torpedo shaped float to prevent mast inversion when the inevitable capsize occurs. The board probably hinged in the middle so when capsize occurs the float sits under the mast. Trimaran idea I like but very low budget project.
  11. ABoatGuy
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    ABoatGuy Member

    505's are great boats and should you get the chance to sail one you will quickly understand why other posters are discouraging turning it into a "cruising" boat. They are light weight racing dinghys and will not take well to a much additional weight structurally. Taking the jib off is going to screw up the balance considerably. They have swinging boards that will take care of some of it but . . .

    These sort of projects are fun, but in this case, I'd save some money and buy a more appropriate hull.

    Kind of like making a camper out of an F1 car.
  12. Skyak
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    Skyak Senior Member

    What you seem to be leading toward is a wing dingy. Wings could be a useful replacement for the righting lost without the trap, but if you are thinking of using the wing for buoyancy righting I think you will be disappointed. The drag from dipping the wing in the water will out weigh the righting provided and it is too far aft -the boat will trip forward. You will want the wings angled up to stay out of the water and it would be wise to make them to bounce off the water when they hit at speed. The other benefit of angling them up is the improved righting that they will provide in a knockdown. The down side is that wings are not much easier to manage than traps -maybe worse.

    The correct answer is to shorten the sail plan and invest in good sail control/reefing. Since your short main will leave some extra mast, you could make a pendant with a float that is shaped to fare the mast to cut wind drag and keep the boat from being knocked down past 90 deg (this is easier than sealing the mast).

    I agree with you that some lead at the bottom of the dagger board is worthwhile if only for the self righting rather than having to climb out on the dagger board for a dunk in cold water. A less effective but more versatile option is water ballast low and centered, for single-handing.
  13. CT 249
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    CT 249 Senior Member

    OK, I'm going to go against guys I respect here, and say it could be possible.

    As an analogy, the two classes here that are closest to the 505 - the Flying Dutchman and the Lightweight Sharpie - have both been turned into mini-cruisers with success. I've never found many details of the FDs with a cabin, but I have some info about the Sharpie with a cabin, aka the Usual 20. It has a standard Sharpie rig, may have an alloy CB rather than the usual glass one, and a medium-size cabin. The hull is just the standard very skinn (4'6"-ish beam) Sharpie hull with a bit more freeboard. There used to be a class of them at one club in Adelaide, where they raced on the windy and rough Gulf with few problems. The one in this pic has a higher cabin than the norm;


    A former Canoe sailor here has altered a Sharpie into a nice daysailer just by fitting a small rig. Another Sharpie was altered into a trailer sailer, along the lines of the Usual 20s which were built as Usuals but without the added freeboard (IIRC) and became a bit of a legend in Queensland.

    Historically both the FD and Sharpie (in its original 12 Sq Metre 'heavyweight' version) were designed to be used for camping cruising as well as racing. The 505 wasn't, but personally I can't see why the 505 couldn't do what the Sharpie and FD can do.

    The 505 is beamier and heavier than the Sharpie, although shorter, and could be an interesting lightweight camper. Putting on enough ballast for self righting is problematic as others have said, but a little bit of weight to steady the boat down is practical.
  14. PAR
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    PAR Yacht Designer/Builder

    It's difficult to make a 16' dinghy a cruiser, simply from an ergonomics point of view, even if the weight of the cabin is kept down. Comparing light weight 20' boats with a relatively light weight 16' boat, just isn't reasonable as the typical 20' boat is literally twice the boat.

    As far as self righting resistance, a keel with a bulb isn't as effective as you might think, until it's heeled over at uncomfortable for novice sailor angles.

    You can make anything into about anything, though these dinghies will sail like crap if burdened with much more then a fabric dodger. A cruiser should have a lot of stowage space, impressive AVS, modest SA/D but with light air options, should tend to steer and handle with authority, but without razor thigh helmsman attention to keep a straight course, if only so you can grab a beer from the cooler without the puppy rounding hard as you do, plus countless of the things these dinghies just can't dream about.

    A free hull is little more then a flask of which to pour money into. You can start with one well suited, so your expenditures go directly toward you goals, or you can attempt to make a silk purse from a sow's ear, where much of the funds will go to conversion, modification and other not directly related to kicking back and enjoying a cold one, while lazily holding a calm helm, on a docile boat.

    Look at it this way, you probably could make an RV out of a Jaguar E type, but you're not going to like the resulting end product. For this project you'll want a Volvo wagon, maybe a V60 so it has some sportiness, but most importantly the volume and capacity necessary to better serve it's RV function.

  15. milessmiles
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    milessmiles Junior Member

    I only used the word cruiser because it wont be raced. Many dinghys are sailed for pleasure, been caught out in two squalls this year and didnt swim. Why on earth do people post comments and advice without reading and thinking about my original and subsequent posts. When did I ask for a cabin or to take a family out to sea? Guess i'll just get on with it.
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