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Thread: Seaford Skiff Hull Thickness?

  1. #1
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    Default Seaford Skiff Hull Thickness?

    I am seriously thinking of building a Seaford Skiff. Ketchum plans from Mystic, on the way. Thinking of cedar strip hull build. I am not familiar enough with planking from scratch and plans will be a bit sparse on detail I think. From what I have researched there appear to be lapstrake versions, but again, setting that up would be, well, new to me from scratch. Seems like I could strip build, glass and epoxy inside and out. Questions for anyone who would like to weigh in - Is cedar strip a viable idea? And if so, how thick should the cedar strips be? Appreciate any help. Study plans below - (Not the Ketchum ones but close enough).

    Screen Shot 2021-11-06 at 7.21.55 PM.jpg

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    Default Re: Seaford Skiff Hull Thickness?

    14 feet...maybe twice scantlings of a stripper canoe?
    What was the original use of this boat? working or yacht? cuz she seems stout.
    A stripper will have no need for all the framing, but you will still have need for structure for the step and trunk.
    ...If she is built too light, as in weight not strength...?

  3. #3
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    Default Re: Seaford Skiff Hull Thickness?

    Originally designed for duck hunting - Great South Bay, LI. Much like a Sneak Box or Melonseed (NJ). Shallow draft for marshes but meant to stand up in a blow - winter time use. Intended use for me is to sail in like conditions - not for hunting. I was thinking it needs to be "stout", as you say. Will need to be pulled up on a shore, and some sort of trailer.

    Thinking cedar for longevity and lightness. Means she will be faster under sail than something heavier. The glass will strengthen it. Seems like the framing is a must to maintain shape under stress? I can adjust the scantlings to keep them "thin" I suppose.

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    Default Re: Seaford Skiff Hull Thickness?

    The 8 foot Atkin dinghy I'm lofting is meant to be strip planked with cedar and covered with canvas. The designer specifies 3/16" thick cedar strips, if that helps. Frames 3/8" by1" white oak on 4" centers.

    Nice looking boat!

    Mike

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    Default Re: Seaford Skiff Hull Thickness?

    Frames on a strip built boat...
    How you gonna glass over those frames on the inside? The strength derived from the inner glass IS the same as the strength derived from frames.
    Bulkhead or a pair of lamminated ring frames at partners and CB trunk yes, but not framed throughout.
    The 8 'Atkin?...this is a strip PLANKED boat,no? not strip built. Before epoxy made inside glassing possible.
    bruce

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    Default Re: Seaford Skiff Hull Thickness?

    I was thinking 3/8" also as a first option. But checking in with others that know more than me. The cedar and glass would be quite strong I imagine - a crude stressed skin composite. Atkin Dingy? Nice boat also.

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    Default Re: Seaford Skiff Hull Thickness?

    Get hold of a copy of this book. It will allow you to calculate all your required scantlings.

    https://www.gerrmarine.com/ELEMENTS_..._STRENGTH.html

    Alternatively search the forum for Melonseed skiff, almost similar in size, and see what those builders used.

    Nick

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    Default Re: Seaford Skiff Hull Thickness?

    Bruce - My terminology is, as you point out, incorrect. I was thinking a "strip planked" boat. As far as the frames, I have never built a "strip built" anything so am not sure how strong that construction method is without frames for a boat like this and its intended use. It isn't a canoe. meaning it will likely see some considerable stress with wave action, beaching, mast stress, internal weight movement, etc. Dunno, that's why I am asking.

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    Default Re: Seaford Skiff Hull Thickness?

    Nick, thx. Excellent, I will. Btw, I originally started with the Melonseed as the build. There is much more info available on them. A lot more around too. Apparently there is boat builder making them in all glass too. There are standard planked and lapstrake ones but no strip planked ones I can find. I will be looking more though. Just prefer the Seaford. I have a good friend who had one and speaks highly of them for the kind of place I will be sailing it. he did not build it though.

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    Default Re: Seaford Skiff Hull Thickness?

    Here is the one at Mystic Seaport.

    HELENPACKER_081316_0142PSweb.jpg

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    Default Re: Seaford Skiff Hull Thickness?

    I built my 18' fantail launch with 1/2" strip planks. Works fine.
    Also just built a 16' Jericho Bay power skiff with the same.
    Planking with western red cedar.
    Fiberglass inside and out adds a lot to the strength.
    I was born on a wooden boat that I built myself.
    Skiing is the next best thing to having wings.

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    Default Re: Seaford Skiff Hull Thickness?

    I previously owned a strip and glass Melonseed. The flat plank keel was plywood, I believe the hull was 1/4" cedar glassed on both sides. She had no frames, just bulkheads at both ends of the cockpit and knees under the deck. She was lovely, light, fast and stiff.

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    Default Re: Seaford Skiff Hull Thickness?

    I think you’re talking about strip composite construction, where strip planking is glued together, with structural glass or carbon sheathing on both sides of the strips and minimal interior framing.

    I’ve recently built in strip composite a 16’ peapod, a 17’ fantail launch and a 22’ fin keel daysailer. All had strips of 5/16” to 3/8” thickness. They’ve had no problems.

    For that boat, I’d think of 5/16” strips of Alaskan Yellow cedar with 10-12 oz, glass cloth in and out.
    Some interior framing across the tunnel might make your floorboards easier. I’d double up the glass in the region that includes the mast step, chainplates and centerboard trunk. The centerboard trunk should be tied into the deck.

    If you want a more detailed analysis, get Dave Gerr’s book on Boat Strength.
    Last edited by JimConlin; 11-27-2021 at 07:32 PM.

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    Default Re: Seaford Skiff Hull Thickness?

    Unless you've already found it, EyeInHand (Barry) a forumite posted this thread about building a pair of melonseeds a while back. http://forum.woodenboat.com/showthre...way&highlight= . His website is also worth a visit http://www.eyeinhand.com/category/melonseeds/

    Nick

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    Default Re: Seaford Skiff Hull Thickness?

    Thx everyone - been a while. I thought it best to build a model of a Seaford Skiff before I messed with full scale. Plans from Mystic Seaport (Ketcham). Tried to build it properly, so I knew how to approach the big one - mahogany stem, keel and transom. Won't varnish so much on the full scale, but when I see mahogany, I just think varnish. Cedar plank, edge glued, frames only on the stations (half as called for). Deck beams, mast step, , etc. oak. Sail is masking tape! Anyway, I learned a lot. Now - I am off to loft the big one.


    IMG_0636.jpg

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    Default Re: Seaford Skiff Hull Thickness?

    nice looking boat.

  17. #17
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    Default Re: Seaford Skiff Hull Thickness?

    Excellent model making skills in evidence too.

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    Default Re: Seaford Skiff Hull Thickness?

    geebus you built a proper model ! de actual bote be a piece o cake now ,gahnonteee.

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    Default Re: Seaford Skiff Hull Thickness?

    When you say "cedar planked edge glued".. are you thinking strip built vs strip planked yet ?
    Or glassing or not glassing the inside ..before/after the "frames on stations"?
    Are you up to speed on the self beveling aspect of a lammed in place frame as opposed to a frame lammed to a mold which will need beveling in order to fit square to the centerline, as a molded frame would.?

  20. #20
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    Default Re: Seaford Skiff Hull Thickness?

    Nicely done! Keep us posted.

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    Default Re: Seaford Skiff Hull Thickness?

    The "frames" I put in the model were for appearance - a vanity really. For the full scale build it would be cedar strip built, glassed inside and out. From all my "research" that would be a pretty stiff hull to begin with I think. I would need some frames at the mast, centerboard trunk forward, cockpit fore and aft for added stiffness/support. Hanging knees for the side decks. Floors for the aft bilge and maybe to support some floor boards if I choose. Frames are a good question though. Any more "on the station lines" would be for appearance i suppose, and be a nuisance for seating on! Mulling that one. My best thought so far would be to either steam bend, laminate or sawn maybe, into the inside before glassing. I am sure they can be lighter than the plans call for, which are spec'd "plank on 3/4" oak frames." Have to epoxy them in I am thinking, then glass. Any more thoughts are welcome! I am in the process of lofting now so I will try to keep this updated. Some more model process phots for fun ...

    IMG_0497.jpg

    IMG_0588.jpg

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    Default Re: Seaford Skiff Hull Thickness?

    As a data point, cosine wherries are 14 LOA 54 inch beam, and use 1/4 inch strips and 3 pieces of glass in and out. plenty strong enough and hundreds have been built over 50+ years. the glass inside and out takes away the need for frames or ribs. you would need bulkheads, decks and knees to tie in the centerboard and mast structures, but no ribs.
    oysterbayboats.ca

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    Default Re: Seaford Skiff Hull Thickness?

    "Btw, I originally started with the Melonseed as the build. There is much more info available on them."
    Articles on
    Seaford Skiffs...if you can find them: Ashbreeze Vol 5 #3 Summer 84, The Boatman #20 Nov/Dec 1994.
    Traditionally constructed.

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    Default Re: Seaford Skiff Hull Thickness?

    If you want the frames not structurally required I think you should have them ,but thin for their width like canoe frames .No problem sitting on those .I would add them after the glasswork is complete ,as trim pieces , lets say , although they would be glued in and add strength too . Their presence would be visually satisfying , perhaps because they would express the transverse strength of the hull that the glass is invisibly supplying .Steam bending them would be more fun than glue lam I think .
    Last edited by Bill Perkins; 03-13-2022 at 07:48 AM.

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    Default Re: Seaford Skiff Hull Thickness?

    I kind of like more widely spaced futtock frames, which can be laminated in halves from spanish cedar or yellow cedar. They can be pretty small, and floor boards can go on top of them. They would look like the frames in the study plans by OP above. Installed after glassing the interior. I would use 3/8" planking strips. I did this in my Matinicus double ender build, though it is lapstrake. Pics below.







    Cricket

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    Default Re: Seaford Skiff Hull Thickness?

    Quote Originally Posted by nickschwitt View Post
    "Btw, I originally started with the Melonseed as the build. There is much more info available on them."
    Articles on
    Seaford Skiffs...if you can find them: Ashbreeze Vol 5 #3 Summer 84, The Boatman #20 Nov/Dec 1994.
    Traditionally constructed.
    Pretty much all the data from melonseeds can get used for the seafords. The main structural difference is the built down stern on the seafords vs the sprung keel on the melonseeds. Secondly the New Jersey boats, whether sneakbox, melonseed or ducker, favored daggerboards rather than centerboards. But the scantling and overall hull shape was the same.
    Ben Fuller
    Ran Tan, Liten Kuhling, Tipsy, Tippy, Josef W., Merry Mouth, Imp, Macavity, Look Far, Flash and a quiver of other 'yaks.
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    Default Re: Seaford Skiff Hull Thickness?

    Pretty much all the data from melonseeds can get used for the seafords. The main structural difference is the built down stern on the seafords vs the sprung keel on the melonseeds. Secondly the New Jersey boats, whether sneakbox, melonseed or ducker, favored daggerboards rather than centerboards. But the scantling and overall hull shape was the same.
    Thx Ben. After much more research I am finding the same. The Melonseed is so close and there is so much more on them. Interesting link here for a fast and furious build of a Melonseed btw ... "damn the torpedos" ... http://traditionalsmallcraft.com/Fil...easy%20way.pdf

    On your note I do find the Seaford transom an unusually appealing variation and prefer the centerboard for the thin water here in Coecles Harbor. At this point it looks like cedar strips 3/8" thick x 3/4" w, glassed inside and out. I'll mock some up. Thinking I will make the bottom keel in two pieces, sandwiched, start with a 3/8" or 1/2" so I can glass over from garboard to garboard, then add the bottom plank to get to the final 1 1/4" dimension. frames would be a vanity addition later if I decide. Am almost finished lofting, while I ponder the seemingly endless clash between bead and cove strip vs. beveled!

    Lofting.jpg

  28. #28
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    Default Re: Seaford Skiff Hull Thickness?

    Progress on the Seaford Skiff. Lofting was difficult as there is the bare minimum of info on the plans. Many errors in the offsets as well. Building the model first was a big help finding discrepancies, but full scale makes them VERY, well, bigger. Major stem and stern laminations well smoothly and have everything leveled now, molds true out with batten tests. Looking quite fair - I am amazed. Decided to use mostly Doug Fir for the structural elements so far as well as the transom. Sourcing affordable and available mahogany is cost prohibitive these days and I will be glassing everything. Also, the boat will be painted so varnish is out except for some trim. Am going to mockup two thicknesses of cedar strips for the hull - 1/4" and 3/8". Do some destruction testing to see if I can get away with bead and cove 1/4" x 3/4". We shall see. Thinking that together with the hanging knees under the side decks, floors as per drawings (also supporting floor boards) as well as framing aft, at mast supports and centerboard trunk there will be a good bit of structural integrity throughout. Have been researching Melonseed Skiffs and, as they are so similar, it has been a big help. Some pics.
    Attached Images Attached Images

  29. #29
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    Default Re: Seaford Skiff Hull Thickness?

    Cool!

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    Default Re: Seaford Skiff Hull Thickness?

    You are going to strip build the hull, but are following the framing/keel scantlings for a carvel version ?

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    Default Re: Seaford Skiff Hull Thickness?

    Following

  32. #32
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    Default Re: Seaford Skiff Hull Thickness?

    I reduced the scantlings/dimensions a bit on keel, stem and stern/transom. the photos show stem and stern before I trimmed them down.Trying to maintain the scale/appearance, but as you note the original scantlings are way over structured for the strip hull. Laminations are plenty strong. Also keeps some weight out of the ends. Using Doug Fir (lighter than mahogany or oak) for structure.

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