23' Motor Sailer w/standing headroom

Discussion in 'Motorsailers' started by kvsgkvng, Aug 21, 2018.

  1. kvsgkvng
    Joined: Jan 2012
    Posts: 212
    Likes: 8, Points: 18, Legacy Rep: 49
    Location: *

    kvsgkvng Senior Member

    Here we go with a yet another dream "pocket' sailboat. This time I wanted it to have standing headroom for 6'-0" person, be self-bailing and self-righting (when all closed-up), have about 1.25 ton payload capacity and suitable for blue water short passages in decent weather. Also, I wanted it to have just more than 1'-0" draft with board up. The engine is outboard as the room inside is limited.

    The traditional construction is envisioned out of marine 4' x 8' x ¼" plywood acting as a form+inside liner with following reinforced epoxy fiberglass overlay(s) for strength. Also flat sheet construction is suitable for aluminium welding (all green ^_^)

    If I am able to insert direct video clip links, I will add them later.

    All and any advice would be very welcome and met with humble attention.
    Thank you.

    2018-08-20_23-07-11 https://www.flickr.com/photos/142944091@N08/42359382620/in/dateposted-public/
    2018-08-20_22-52-29 https://www.flickr.com/photos/142944091@N08/43449479154/in/dateposted-public/

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  2. rwatson
    Joined: Aug 2007
    Posts: 5,821
    Likes: 270, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Having gone through a similar project process with similar aims. I think you have gotten a lot of the design right.

    My concept was a 28', with the hull more optimized for power.

    The only "issues" I see are
    1) The stern skeg. This is pretty redundant with a stern hung rudder, with kick up ability, and may give you problems with tight maneuvering.
    2) The outboard. That is going to need to be offset, which limits the power/weight quite a lot. You may like to consider twin hung rudders with the outboard in the centre.
    3) It looks like you have a daggerboard right in the middle of your companionway. Get some cardboard and old plywood, and mock up the entrance. You will see that it will be a major headache. You might want to consider a folding centreboard along the keel in preference, much like the earlier model Macgregor trailer sailers.
     
  3. kvsgkvng
    Joined: Jan 2012
    Posts: 212
    Likes: 8, Points: 18, Legacy Rep: 49
    Location: *

    kvsgkvng Senior Member

    Thank you for you advice. I agree with your comments, the problem is how to accommodate all of them without losing anything... So, after trying to arrive at the compromise, I ditched whatever folding/lifting mechanisms and changed design according to your comments:

    1) Removed long skeg and left only a piece to reinforce the rudder.
    2) In order to have symmetrically placed outboard of considerable weight, the rudder becomes part of the skeg and gets under.
    3) No daggerboard/centerboard -- all discarded because of its mechanical nature. Those things break, require maintenance and are not adequately reliable, especially out of reach repair facilities.

    With these limitations and desire to have as shallow draft as possible, I have modified layout, but when I started to add-up weight numbers calculation, it appeared that the displacement is not sufficient to meet the design displacement at first iteration. The weight calculations were based on assumption of being two months out to sea and covering approximately ( 0.5 gal/hr @ 6 knts/hr, i.e. 120 gal x 2 x 6 knts x 1.15 ) more or less 1500 miles of "put-put" motoring. If I am in the ballpark, the boat needs another 0.3 ton of displacement. I attached weight calculations and would be most appreciative if someone could suggest/correct these numbers. Can anyone please help?
    Again, with respect, awaiting someone's help. Thank you.

    Video(s):
    23x8.5_Motorsailer_Bilge_Keels https://www.flickr.com/photos/142944091@N08/42402356020/in/dateposted-public/
    23x8.5_Mororsailer_Lines https://www.flickr.com/photos/142944091@N08/43304775545/in/dateposted-public/

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    Attached Files:

    Last edited: Aug 23, 2018

  4. rwatson
    Joined: Aug 2007
    Posts: 5,821
    Likes: 270, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Well done.

    I think that is a really useful configuration. You will be able to "stand up" on beaches, which is always handy.

    Based on my design spiral experience, I am afraid you will have to go a longer hull.
    Adding another three feet will not add that much expense or build time, but it can greatly expand your interior.

    I ended up going to 28ft, which is still trailer able.

    Another idea that you could implement. You wont need to make those skegs solid. Ballast with the 8.5 feet beam isn't going to be a big issue for the stability curves.
    so
    How about you make them hollow, and store fresh water in them, or fuel. In fact, the entire "wasted space" under the cockpit floor could be tankage, as would under the forward berth..

    Regarding the cockpit floor, I am assuming it will be self draining. Otherwise it could be a real problem when swamped.
     
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