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Discussion in 'Projects & Proposals' started by John Torelli, Oct 12, 2022.

  1. John Torelli
    Joined: Oct 2022
    Posts: 5
    Likes: 2, Points: 3
    Location: San Diego, CA

    John Torelli Junior Member

    Hello to everyone, I'm new to this forum and excited to learn it exists. Before I post my question I will share my boating experience. I grew up on Long Island, NY which offered various boating activities and different style boats. I spent the past 40 years on the west coast mostly in southern California where my wife and I enjoyed different types of boating including trailered center consoles, small cabin cruisers, trawlers (three Nordhavn's & one Helmsman) and my current boat a 16' Marshall Marine Sandpiper sailboat. I have written articles for different boating publications, a small book focused on Living Aboard and contributed to the book Voyaging Under Power - Fourth Edition.

    Fast forward to 2022 and I'm learning something different "sailing" which is interesting and will likely remain on a small scale. While researching different style sailboats I discovered "Catboat" designs from the late 1800's offer large beam to length ratios (almost 2:1) and are very stable boats. I'm interested in playing with this hull shape and seeing what can be accomplished with a new deck mold to develop an Eastcoast Style Picnic boat. While the exact Catboat size is still TBD, I have a few thoughts and looking for someone interested in helping me sketch something which could be shared on this site.

    From a performance perspective I'm not looking to push the envelope of existing hull designs and accept current speed / range equal to FD hull speed. I have my thoughts on the seaworthiness the boat could be and potential uses but doing this project for fun.

    Appreciate all inputs and interest. thank you.

    John T. - Nordhavn 4050, 4061, 3522 & Helmsman 38E - former owners. Sandpiper 16 - current owner.
     
  2. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Length to Beam..
     
  3. John Torelli
    Joined: Oct 2022
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    Location: San Diego, CA

    John Torelli Junior Member

    Thanks for correction "length to beam" the other way would definitely be a strange looking boat. :)
     
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  4. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Welcome to the forum John.

    I'm not sure a low length to beam catboat is the right boat for SoCal. The sheltered "downeast" coast of the Atlantic northeast is very different from the exposed iron bound coast of the west, even if you are south of Point Conception in the Southern California bight. Inside SD or SF Bay maybe, but not offshore.
     
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  5. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    I've only been there a couple times; one of them was 10' fastish seas not far out of San Diego Bay with a 'gentle' 15 knot wind. About a third of the people on board got sick.
     
  6. John Torelli
    Joined: Oct 2022
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    Location: San Diego, CA

    John Torelli Junior Member

    While I agree the seas are different (east coast versus west coast) and have enjoyed both in small boats. On the west coast we have enjoyed our full displacement trawlers with and without stabilization. Most of our travels were up and down the coast within 20 miles of the coastline. I'm new to sailing and have a lot to learn so my questions and logic may not align with the reality of sailing so correct me when I'm wrong. When I look at sailboat monohull designs in general, I see many long skinny hull designs. I selected the Catboat for its large beam (similar to a FD trawler) which has already impressed me especially for its initial stability and limited sailing experience. My planned use for this boat is "inside bays" but would not hesitate to take her outside on calm days. Around here paddle boarders, jet skis and small skiffs messing around outside the inlets is common. We have not long-distance cruising planned for this little 16'. A few hours during the daytime will be our limit.

    I'm curious why a Catboat is not a good choice for west coast sailing as long as the owner monitors the weather. I'm guessing you are referring to the swells we live with but are usually spaced well apart. Getting hit on the beam is uncomfortable without stabilization even on a 50,000lb trawler so I can understand the same concern with a lightweight sailboat but what else am I missing specifically related to the "wide beam" aspect of a sailboat? I would think our wide beam catboat is safer and more comfortable than a narrow hull sailboat assuming the correct amount of sail for wind. Thanks

    John
     
  7. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Actually, it's the other way around; especially with a typical centerboard catboat. Wide shallow hulls, even heavy ones, depend on form stability, rather than BG geometry, to carry sail. This has the effect of also making them wave followers (i.e. they tend to want to conform to the face of the wave).... this means that in higher energy environments motions are closely locked to the wave face and more extreme, especially in periods near the natural period of the vessel (~5-9 sec). This is not to say that a competent mariner would be unsafe in a small catboat on the west coast, but with deep water right offshore and an onshore set, there are better choices for the typical SoCal sailor wishing to venture out of the bay.

    Below are today's wave spectra off Boston (44013) and Pt. Conception (46054). Based on experience with these things, both are fairly typical of their areas. Notice that the west coast has much longer average period (5.2 sec vs 3.8) and much more energy (area under the curve) even though the significant height is about the same (3.9 ft vs 3.6) due to the east coast spectra being fairly narrow banded while the west coast has the typical Pacific swell.
    upload_2022-10-13_11-6-39.png
    upload_2022-10-13_11-7-15.png
     
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  8. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    Jehardiman is right, wide boats tilt when the waves pick them up from the beam where a ballasted skinny boat will tend to stay upright, even on the face of the wave.

    However, sailboats have the advantage of sails to reduce much of the back and forth rocking. They also have limitations in angles to the wind. Which means you will rarely be sailing into the incoming sea, but should try to maintain an angle just off the wind and not directly into the waves.

    Fat boats lift quickly with the oncoming wave, even when pointing into them, where a skinny boat will be cushioned by the narrower bow.

    It is mostly about comfort, not seaworthiness. The Clark Mills Suncat is a very seaworthy boat, but when he designed our live aboard schooner, she was 56'x12' and a very stable vessel in a storm.
     
  9. John Torelli
    Joined: Oct 2022
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    Location: San Diego, CA

    John Torelli Junior Member

    Thanks for the education which for me is never ending. I think I understand the explanation and agree a deeper draft provides benefits. Our Nordhavn trawlers had deep drafts combined with heavy ballast and still roll in any beam sea. While stabilization helped a lot there were times when we preferred to be in port. When I look at other oceangoing designs including the Dashew with a long and narrow hull for speed I see "some" comparison with the sailboats and your response above.
    Our Nordhavn 40 was about 40' LOA and 14'10" beam (one of the wider boats) and our Sandpiper is 15'6" long and 7' beam. Recognizing totally different designs and boats they both offer large beams. I can see the N40 being able to handle a beam sea this due to its ballast and 5' waterline even without stabilizers. With the Sandpiper we still have 16" draft without the center board and 3'9" with the centerboard deployed. Thats a lot of daft to help keep the boat from flipping over in a beam swell or is not enough for its hull shape / design?
    From a size ratio perspective, one could argue the smaller Sandpiper has greater or more draft than the larger N40. So, with this in mind is the Sandpiper better than say the N40 "if" we shrunk the N40 to similar LOA and Beam? I'm trying to understand the true seaworthiness of the Sandpiper compared to a full displacement power boat of similar size (may not be practical but hang there with me). I would think the Sandpiper is a better / safer design but need an expert to confirm. Once I understand the right answer, I will hit you up with the next round of questions. Thanks again for taking the time to help educate others.

    John
     
  10. John Torelli
    Joined: Oct 2022
    Posts: 5
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    Location: San Diego, CA

    John Torelli Junior Member

    I almost forgot, is there anyone out there who would be interested in sketching a small open launch boat which have pictures of the hull and need a little assistance playing with the deck and adding a downeast style window frame. Just trying to get an image on what this may look like. Thanks
     
  11. Dolfiman
    Joined: Aug 2017
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    Location: France

    Dolfiman Senior Member

    I have sketched a dinghy inspired by a traditional East coast APBY 14' Catboat , with such L/B =2 , it is the example D6 among the ones given in illustration of the application Gene-Hull Dinghy :
    Gene-Hull Dinghy 3.0 version, and post-applications Stab and VPP in connection. https://www.boatdesign.net/threads/gene-hull-dinghy-3-0-version-and-post-applications-stab-and-vpp-in-connection.66426/
    Home | Arey's Pond Boat Yard https://areyspondboatyard.com/
    By using the applications (just required Open Office) , you should derive a 16' version (your objective as I understand) and then refine it at your convenience.
    About a traditional cat-boat in chop sea : to my opinion, the main drawback is the weight of the wooden mast positioned very forward in the bow volume. If you can adopt a modern carbon mast and positioned more backward, you will improve a lot the boat behaviour when upwind in head waves
     
  12. Will Gilmore
    Joined: Aug 2017
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    Location: Littleton, nh

    Will Gilmore Senior Member

    Why would that present a problem, rather than add to the comfort and reduce bow-on wave induced movement? I don't have a lot of experience with traditional cat boats with heavy wooden masts, but I would expect the weight of the mast and the wind pressure on the sail, to dampen pitching from the waves. Perhaps there might be a tendency to dig the bow into the next wave, when coming up out of the trough, but the hull should be designed to balance that effect.
     
  13. Dolfiman
    Joined: Aug 2017
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    Location: France

    Dolfiman Senior Member

    I have not myself direct experience with traditional cat-boat, but experienced with keel-boats and practically to have too much weight in the bow is always a disadvantage for the pitching behaviour. At contrary, you should search to minimise the mass moment of inertia Iyy and so weights in the boat ends or a heavy rig (a normal rig contributes for about 40% of Iyy) is to avoid as much as possible. So, a heavy mast in the bow is twice to avoid I would say.
    Back to tradi cat-boat, I can quote similar opinion from experts, here extracted from the excellent Sailcraft blog of our colleague member @CT249 :
    "In typical cat-rig fashion, the mast was stepped right forward to avoid creating too much weather helm. Because the foredeck is too narrow to allow an adequate staying base, the archetypcal cat rig has no shrouds, which in turn dictates a strong and heavy mast and mast step. The traditional catboat was therefore heavy in the bows and had a reputation for pitching badly in a seaway. "
    "In a sea, however, the heavy mast, stepped so far forward, makes the boats plunge dangerously, and the boats themselves are so shallow that they are not very well adapted for smashing through a head sea. "
    SailCraft Pt 1.3: “A little too marvelous to be real” – the story of the Una Boat https://sailcraftblog.wordpress.com/2016/05/20/sailcraft-pt-3/
     
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  14. DogCavalry
    Joined: Sep 2019
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    Location: Vancouver bc

    DogCavalry Soy Soylent Green: I can't believe it's not people

    My Saturday morning read. Anything is interesting if the folks telling you about are intelligent, eloquent, interesting. I love this forum!
     
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