Reverse Engineering (conversions And Modifications)

Discussion in 'Boat Design' started by viking north, Dec 25, 2010.

  1. hoytedow
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    hoytedow Wood Butcher

    Look at the upper right of your last post: It says Rep: 90.
     
  2. viking north
    Joined: Dec 2010
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    Location: Newfoundland & Nova Scotia

    viking north VINLAND

    Michael, grp, hull, plastic tanks,and like all my past builds, wood framed superstructure.The sheeting, decks cabin, 1st. layer mahogony ply(epoxy coated upturned surface and edges, next airex foam sanwich, final layer grp., gel coat sprayed or rolled finish. Airex not so much for heat insulation but to prevent humidity drip on the interior. I am into my first year on the build part time and have most of the prep work ready to install the full keel (with cut out to ease coming about). 316 stainless keel bolts arranged in pairs encapsulated in poly.resin with the automotive wheelweight ballast.You're right re getting paint to stick on stainless, i rough it up with a random orb. sander using #60 grit to take the shine off, let it set for a couple of days and then paint, bonds much better but even that is more sustiable than on other metals. Geo.
     
  3. michael pierzga
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    michael pierzga Senior Member

    Im not familiar with custom grp boats. Why plastic tanks ? Why not integral grp epoxy tanks for water and waste ? they save much space , you can get them lower in the bilge and they act as double skin , waterproof, bulkheads . Do Glass boats have integral tanks ??
     
  4. viking north
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    viking north VINLAND

    Michael, using plastic tanks(square food containers) 20gal. $10.00 ea, and they fit under the settees. one each side. Lose a little space due to the turn of the hull but can live with that for the price. This is my own boat, a big grp. surfboat hull which i am converting into a motorsailer.Some grp boats have integral tanks some don't depends on the manufacturer. Geo.
     
  5. viking north
    Joined: Dec 2010
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    Location: Newfoundland & Nova Scotia

    viking north VINLAND

    Ships Lifeboat conversion to Motorsailer

    THE FOLLOWING BUILD PRESENTATION IS A "AS I DID" ILLUSTRATION ONLY AND SHOULD NOT BE USED AS AN ENGINEERED REFERENCE FOR AN ACTUAL BUILD. As promised my 2nd. Conversion, 26ft.x8.5ftx5.5ft alum. ships lifeboat to motorsailer, launched year,1992, sold year,2000 for a planned trans Atlantic crossing. Photos will continue to be posted thruout the week as i find time. At this point in the build the hull had been steam cleaned of about 10 layers of white marine paint and was in transport to the shop on Newfoundland's south west coast.Geo.
     

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  6. BATAAN
    Joined: Apr 2010
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    BATAAN Senior Member

    How nice to find an aluminum lifeboat to convert. What rig and motor did you wind up with?
     
  7. viking north
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    viking north VINLAND

    Battan, take it from me don't ever convert an aluminium hull, what a pain, too thin to weld had to use marine rivets and 3m5200 but it worked never did have a leak. I am posting the entire build beginning to end so all the info will show but don't be shy ask any question you wish. A few more photos will be posted tonight.Geo.
     
  8. BATAAN
    Joined: Apr 2010
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    BATAAN Senior Member

    I learned long ago not to convert life boats unless they are fiberglass or wood. All the metal ones are too thin. Steel ones work when sheathed in Xynol cloth and epoxy and then keep the bilge dry inside but a keel is always a strain on the bottom of the boat it wasn't designed for.
    My son's houseboat is a 1930s 26' lapstrake yellow pine lifeboat hull that's still sound.
     
  9. viking north
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    viking north VINLAND

    Ships Lifeboat to Motorsailer Conversion

    At this point white oak floor shaped floor timbers 3in.x6in.xfull beam at the floor, spaced on 20in. stations are already installed. These were epoxy coated and cross bolted to the existing alum. floor webs with ten 3/8 dia. stainless bolts each. The floors were then drilled to receive the keel bolts and the hull inverted.
     

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  10. viking north
    Joined: Dec 2010
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    Location: Newfoundland & Nova Scotia

    viking north VINLAND

    Battan, This is #2 conversion, my first was a 30ft. wooden Newfoundland trap skiff, that was much easier but again someone offered me a deal i couldn't refuse. My present conversion is a beautiful big fiberglass surfboat hull. I will be posting it also but a little later say in the late spring, but if you want private photos i can e mail to you as i build. Geo.
     
  11. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Ships Lifeboat to Motorsailer Conversion

    This photo shows what i call the Ballast cage. The 5/8 stainless keel bolts are fed down thru the floor timbers with just 1/2 of the thread showing,and the base of each bolt where it penetrates the hull bottom is surrounded by a ring of 3m5200. The heads of the bolts pertrude thru the floors just enought to install the big stainless washers and allow screwing the nuts level.The keel bolts are then bent inward to meet and be welded to a sced. 40 stainless pipe.This is just one section of the cage, another piece was installed to run the entire length of the planned keel. Notice that the pairs of keel bolts at each station when welded to the pipe and bolted thru the floor timber form a triange , the strongest possible mechanical setup against transverse stresses.
    If you're wondering what those sleeves on the keel bolts are they are not welded joints the keel bolts are re cycled 316 stainless outboard motor drive shafts custom threaded on one end . The sleeves are some sort of sweated on guides. Gotta scrounge what one can to save money.
     

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  12. viking north
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    viking north VINLAND

    Ships Lifeboat to Motorsailer Conversion

    This shows the pre built alum. keel shell dropped down over the Ballast cage. Because i didn't have a tig welder, (Lower heat to prevent warping ) and was strapped for cash, I decided to rivet the keel shell flange to the hull using 3m5200 as the bedding compound. 300 blind, 3/16 monel pop rivets later it was fastened and never a leak for two reasons, the 3m5200 and the 3000lbs. of lead auto. wheelweights ballast was installed encapsulated in polyester resin. The ballast was installed thru 3in. holes, spaced about a foot apart, cut into the bottom of the keel shell. Once all the ballast was installed i topped the holes level with resin and installed a plastic keel shoe over it all. I first poured in about 5 gal of resin and let it set before adding layer upon layer of weights and resin. The initial layer of resin didn't leak down thru the keel bolt holes because as i stated prev they were sealed with a ring of 3m5200. Believe it or not i distributed the ballast fore and aft of midships by gut feeling only(CGT, center of gut feeling). The weight had to be distributed in such a ratio as to ballast the stern 1 foot lower than the bow. This is the recommended emersion when converting the symetrical hull of lifeboats to sailers/motorsailers. Before launching and again by gut feeling i painted her waterline and when launched Neptune was on my side, she wasn't 1/2 in off her lines, no trim ballast necessary, Now thats luck.
    Notice the red lines on the keel side, those were the two angular options i had for the shaft tube which was by the way all installed prior to fastening the keel shell in place and installing the ballast.I seem to remember it was around 12deg.Sorry i have no photos of this. The very back of the keel shell was mig welded to the existing origional keel and to the hull at the bottom edges but not longitudionally along the keel shell flange to hull joint. I worried about burn thru and warpage from heat.
     

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  13. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Ships Lifeboat to Motorsailer Conversion

    Once the keel and ballast was installed, she was righted and some inital deck framing was started, and once again in my life someone made me an offer i couldn'd refuse, this time on my house and shop. So it was pack it all up put it on the trailer and ship out to greener pastures.Just what a builder needs a move mid build. So 1 yr. 300miles SW later after building a new house and small interm shop it's back to the build near Halifax Nova Scotia.
     

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  14. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Ships Lifeboat to Motorsailer Conversion

    Just found these old photos of some of the deck framing. Notice how some of the webs in the walls have their corners cut out, this is making use of as is construction to serve as the fastening points for the settes Note forward how they have been cut to serve as the base of the double berth. When doing conversions think and plan well ahead to make use of existing structure.
     

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  15. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Viking, very nice and interesting photos. :)
    I see a wooden deck built over an aluminum hull. Can you tell us a bit more about that particular - how did you join the two parts and materials, what surface coating/protection did you use, how did it behave at sea, did you have any problems with leakage, with wood shrinkage/swelling or with aluminum crevice corrosion, etc etc...
    Cheers!
     
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