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Turning Your Hull

On October 11, 2017, in Builder Tips, by tedhanneman
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Editor’s Note: There are many ways to turn your boat and we appreciate Ted Hanneman sharing his version with us. Since Glen-L boats are built upside down, it’s necessary to turn the hull over to complete it at some point. Ted is building the Glen-L CS-20 which is a 20 foot Stitch and Glue design. If you don’t have access to a backhoe or bobcat, man power will also work…

Disclaimer

What follows is my personal experience in building my first boat. These are the techniques that worked well for me under my construction conditions. They are written as an aid to first time builders purely for information. I take no responsibility for their use or misuse or any event positive or negative that may result. If anything in this document is different to instructions given by the supplier/designer, the supplier or designer’s instructions take priority. If anything is unclear, contact the supplier/designer. Above all, work safely. Always wear personal protection equipment: eye protection, and as needed hearing protection, dust mask, and gloves … nitrile or leather as the situation requires.   

I turned the hull last fall and worked on fiberglass, epoxy, the skeg and painting during the winter in my rather cold garage. Needless to say, progress was slow. Turning the hull upside-down is reasonably straightforward, however since the boat is about 500 lbs at this stage, the hull must be cross-braced and diagonally braced. Alternatively, you can install an 8’   2 x 8’ side piece at gunwale level along the widest part of the boat, and cross brace it with at least 3, 2 x 6 beams attached to the 2 x 8. Use 5/16’’ carriage bolts … not screws. While this is not essential for the first turn, it is essential to turn the hull back upright and it is a lot easier to install the structure when the hull is upside up rather than upside down. Note that the 2 x 8’s must be shaped and angled to conform to the hull. Keep the piece you cut off, as this will be needed to turn the hull upright. **

The best method is to find/hire someone with a small backhoe or lifting machine such as a Bobcat®. Pad all possible lift sites, especially the transom cutout and the gunwales. Apply cable and lifting rings to the transom and fit the bow eye with a hardwood load block as backup. Mine is 6 x 2 x 2 birch, puttied and epoxied in place. Reinforce and clamp the aft butt blocks as this is where the major stresses will occur.

Next, prepare 2 safety poles from sound, straight 10 ft, 2 x 4’s with 3/8’’ or ½’’ x 4’’ lag bolts inserted so that 2½’’ (the nut side) remains exposed. Insert these at the 8’, 6’, and 4’ marks. These will catch the gunwale and control the descent as the hull rolls over.

The first step is to find a place where everyone can work safely. This boat is 8’-6’’ wide, you will need an area about 30’ wide depending on the size of the machinery. Have a number of sheets of plywood available to protect the hull and work surface during the operations. 

Remove the cradle by jacking up the front of the hull and getting the backhoe to lift the transom. Replace the hull on the ground and remove the jack block from the bow area. You will need about 5 stout men plus the operator to flip the hull. Start by lifting one corner of the transom. Eventually, 3 men will be able to lift the hull at the chine. Wear protective gloves!  As the chine rises, the 2 other men, with safety poles within reach should block the opposite chine from skidding by blocking the gunwale. As the gunwale digs into the block, the opposite gunwale will come over center and must be caught on the lag bolts in the 2 x 4 safety poles.

At this time the backhoe can release and come round to take the load of the safety poles. Lower the gunwale to the 4’ mark. Then the 5 men should be able to lower the hull to the ground using help from the backhoe if necessary.

Next, prep the cradle to receive the hull by bolting (no screws!) 2, 8’ 2 x 6’s across the cradle to points F and the adjoining H position resting edgewise on the D members of the frame. Make sure they are centered. I strongly suggest that D and J members be made in 2’’ stock to support the load. On the end of each 2 x 6 loosely install a 1 ½’’ x 6’’ mending plate (drilled flat bar is OK) using a 2’’ #10 screw. These will hang down, but when flipped up will be in line with the end of the beam and be higher by 1 or 2’’ than the beam. Have 2 more screws available for each beam end to complete the job.

Place a 2 x 8 beam, edgewise up, near the bow and have it manned by 4 people. Have two robust 5-gallon pails with lids, or some other support available. Pick up the aft of the hull with the backhoe through the transom cutout (or with cables/slings) and the helpers will pick up the bow on the 2 x 8. Transport the hull to the position where it will be replaced on the cradle. Put the ends of the 2 x 8 on the supports (pails or other), and maneuver the prepared cradle under the hull so that the ends of the 2 x 6’s protrude by about an inch or so. Lift the hull as necessary to accomplish this. Lower the hull onto the cross planks, flip up the safety mending plates and finish installing them with 2 more, #10 screws. If you need to move the hull/cradle assembly only push the cradle … not the hull!

Turning the hull (2)               

Turning the hull right side up is a job for professionals with proper equipment (backhoe, crane or similar) and an operator with a gentle touch on the controls. Unless you are in the lifting or construction business yourself, I strongly suggest that you watch from afar, and let the professionals handle the job. Plan on having the job done on 2 separate days, as there is much to do between day 1 and day 2. There will be plenty of prep work for you to do as well. Identify or assign a lift manager and have him/her inspect and approve the crate and arrangements a day or so before the equipment/operator arrives. If he/she suggests modifications, do them and get approval before the equipment is scheduled. This is extremely important, as a clear line of responsibility must be maintained.

Build a frame around the hull with construction lumber. You will need at least 3, 2 x6 x 10’,   10, 2 x 8 x 10’and 3, 2 x 4 10’. Also, you will need about 50, 5/16th x 6’’ lag screws, and a box of 100 5/16th x 3 ½’’ carriage bolts. You will use about 60 to 70 on the job. Also, a 2 lb box of 5/16th washers used with both lag bolts and carriage bolts.  For tools, get a good quality percussion nut driver. I use a 20V DeWalt with a 6-pan high quality socket.

Install 3  2 x 8 x 10’s on edge under the boat and attach them to the three 2 x 6’s you installed before turning the boat over. Use lag bolts and filler blocks if necessary to make a solid attachment. The cage assembly should be somewhat aft of the midpoint, as the hull is heavier aft. Discuss this with your lifting crew before starting. Screw the shaped pieces that you removed at ** in ‘Turning the Hull (1) to the chine with substantial screws, 2 ½ x #10, to give a reasonably square surface to the ground. I call these trim pieces. Yes, you will have to fill the holes after, but they will be under the sheer hooks.

Cut the 2 x 6’s in half and attach them square to the 2 x 8’s, in contact with the trim piece, with 3 carriage bolts . This works best in a triangular pattern, 2 inboard, 1 outboard. The end of the upright should be flush with the bottom of the 2 x 8.

Trim the 2 x 8’s flush to the 2 x 6’s and make sure the 3 ends of the 2 x 8’s are in a straight line. Attach a 2 x 8 board across the ends of the 2 x 8’s with 2 lag screws in the 2 x 8 and 2 lag screws in the 2 x 6 vertical. Do not skimp on lag bolts or you will have a safety issue and a collapsed boat later on. Do the same on the other side.

Next, fit 3, 2 x 8’s across the top and secure them to the 2 x 6’s as described for the bottom. Start one end flush to the upright and trim the other end flush to the upright on opposite side. It is important that the top 2 x 8’s be in a straight line. so use uprights of equal length fore and aft and establish the height of the center beam with builder’s line. Attach a 2 x 8 to the uprights and ends of the beams as you did for the bottom. Cross brace the assembly with a 2 x 4 screwed to the transverse and bolted to the verticals.  These bolts can be 5/16th x 4’’ Similarly, cross brace the 3 2 x 8’s on the top with a 2 x 4 that is securely bolted into the 2 x 8’s that traverse the hull and the longitudinal 2 x 8 that connects the 3 transverses.  It is extremely important to fit this brace correctly with a good-sized triangle at the ends between the longitudinal and the transverse.

Cut and fit a keel support for the aft transverse and bolt it to the transverse with 4 carriage bolts. Likewise, make 9, 8’ ’x 10’’  pads and attach them to the ends of 2x stock (2 x 6 or 2 x 8)  with substantial screws countersunk so as not to damage the hull. Six will be attached to the top frame transverses, half way between the chine and the keel, and three will be attached to the upright 2 x 6’s on the side to which the hull will be turned at a position closer to the chine than the sheer about two thirds of the way. Use at least three carriage bolts on each joint and make sure the braces are snug and flat on the hull. All transverse and upright pieces should be trimmed to have flush ends. Be aware that the frame is square in profile, but narrower in the front than the back in plan. This has implications for the lift.

 The lift manager must inspect the cage and bracing before starting the lift. If adjustments are required, do them. He/she (the lift manager) will attach cables, ropes or chains to the far side longitudinal and lift which will cause the crate to turn on its side. At this point the lift manager may or may not relocate the cables etc. and finish the lift by turning the hull the remaining 90° so it is now resting on its support transverses, sheer side up. As it is expensive to have equipment on stand-by, it is better to dismiss the crew while you prep the next part of the job.

Now, prep the cradle. Remove the 2 x 6 cross pieces you installed to support the inverted hull. If you have wheels, align and tighten the axles. Install carpet on all frame parts that will be in contact with the hull. If the boat must be put into a shed or garage, line up the cradle with the door. Dismantle the crate around the hull leaving it (the hull) resting on the 3 2 x 8’s with the longitudinals still attached. The lift manager will need at least 2, 30 ft lifting slings, which he will fit between the keel and the remains of the crate. As the slings reach the sheer, be prepared to insert a transverse 2 x 6 or 2 x 8 inside the hull to support the inward pressure created by the lift. The lift manager will advise. The lift should be straightforward. Pick up the hull and lay it gently in the cradle. Retrieve the slings and if necessary, get the crew to help you put the boat in the shed or garage. Push the cradle, not the hull.  

Note: One thing I did not do but  that must be done to ensure a safe operation is to diagonally brace the top of the crate before the lift. This is essential as the crate can collapse otherwise. It is not possible to diagonally brace the underside.

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One Response to Turning Your Hull

  1. Chris says:

    Glad this worked for him, certainly the most complicated turning of a relatively small and light boat I have see.
    At least it appears to have been relatively safe. 🙂

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