Return of the Mischievous Poltergeist

Its amazing the things that occur during the construction of such a project ,  tools that you put down for a second amazing disappear for long periods at a time , only to be found later ( or sometimes not at all ) in a totally bizarre place . How did they get there !! . Either a Mischievous Poltergeist is playing games with me or looks like i need to tidy up my workspace again ! .

We have started to skin the BEAST ,

This is the first of the two layers of 12mm plywood , the rear section was done in a single sheet , the forward part is done in 150 mm strips due to the twist in this section ( due to a rather deep forefoot ) . This changeover is also marked in the change in the chine as the connection between the sides and the bottom changes from an overlapping joint to a butt joint .  The strips aren't glued into place as yet , just held by a couple of screws , the angular pattern creates a concave shape in the strips so I let them stress relief in the shape for a day before i glue them  , makes the gluing easier . The second layer goes on using a reverse angle creating a convex curve which holds them  nice and tight to the first layer .

Managed to secure a shipment of marine plywood at a good price , so got a test shipment of 25 sheets , stuff looks good so I will attempt to get some more , but am seriously running out of space , there is now even less room between the boat  and the walls of the shed .

Hopefully should make a bit of progress this week as have manged to take a few days off work , between taking my son to the go-carts , and the other maintenance work that needs to be done around the place , here's hoping anyway .

The Curse of the Second Guess

There are times during the construction that you look at your Creation and Wonder ?
Does that look right? , Should that be Straighter , Bendier ,Smaller or Bigger , Does what looked right  on a piece of paper or a Computer Screen really translate when it forges it way , full size in the real 3D world . You just keep going saying quietly to yourself that your sure its supposed to look this way , even though those niggley questions rattle around in the back of the head to annoy you !.

But slowely it grows on you , Your 3d creation starts to fill in , and you feel more at ease .
Framing for this section is almost complete , just a bit more tidy-up planing to get things nice ,true and ready for the 2 skins of plywood to skin the beast . This framing has been slower than expected , mostly due the laminated stringers,chines and gunwales etc ( only had so many G clamps ) , the next 3 sections ( rest of the Port Hull ) should be quicker as these members will be single pieces of solid timber as there is much less bend and twist to deal with .
Three months down , three more to go for this first section , and then hopefully 4 months for each of the sections to follow , Then all again for the Starboard hull  . Connect the pieces then my creation hits the water , and then the Hard work starts , but hopefully that will be full-time construction rather than this part-time stuff .  There must be easier ways to retire !!

To Scarf or not to Scarf

THAT IS THE QUESTION

This is a typical scarf joint !

Its a Pain ! , takes lots of time to make and to be done correctly , needs a reasonable level of accuracy . I need to do lots of them as the length of a piece of wood doesn't always ( most times in fact) match the length required for the job . This is the two piece lamination of one of Jigsaw's Gunwales ( side top edge of Hull ) . Currently I make them by rough planing the angular cut using a power planer , then fit into a jig I created and using a router to finish the cut to a more accurate version . Originally I used a bench saw to make the initial cut and then finished with the router , but typically my bench saw has quit ,the blade started to wobble more that it should and under investigation found that a small bronze bush had become worn and havn't been able to find a replacement . My tools are failing already !!!  .

Jigsaw by Name , Jigsaw by Nature

As mentioned , Jigsaw's hulls are made from multiple sections  , each approx 5 meters in length and over 2 meters in width . These are required to be joined before they hit the water and the process of this joining has gotten more difficult since the decision was made to build in wood rather than steel . The connection points should be seamless , structurally sound and connect quickly  , not an easy proposal .

Skin connection is relatively simple , the inner skin of 12mm ply will butt up directly against its opposing section , the outer layer is held back 200 mm from this edge and a 400mm panel is fitted across this gap as the hulls are joined together , another layer or (butt block) is fitted on the inside of the inner skin across the 850mm distance between the transverse frames .

This gives 3 layers of ply with staggered joints across this section of the hulls , and is likely stronger than the rest of the hull .

Connection of the Chines , Stringers ,Keel and Gunwales is more complex as these are constructed of lamination's of solid timber , but again one of the lamination's is butt jointed to its opposing section ( outer piece this time )  , the inner lamination is scarf jointed with a additional section added and a inner reinforcing layer of fiberglass is added for additional strength in a U section covering the top and sides of each of the longitudinal structures.

The fiberglass U section provides a stronger connection than a third layer of wood as it attaches to a far greater surface area.

Technical Spec's

LOA      19.8  meters
Beam       8.4  meters
Draught   0.95 meters
Displacement   38000 kgs
WingDeck Clearance 1.2 meters

Main Power  2  x   150 hp Inboard Diesel

Hull Construction is Ply ( double skin 12 mm marine ply ) over Frame with an outer Layer of Fiberglass , Framing is longitudinal stringers over transverse frames and watertight Bulkheads .

The Beast Reveals Itself

After 8 weeks of Part-Time work ( Evenings and Weekends ) the shape of the beast is finally revealed , well the first 5 meters of it anyway .  Jigsaw's hulls are created in separate sections to be joined at a later stage , you may notice the rather wide stem , this is the base of the conical bow section  to be constructed using a vertical strip plank process . Originally the houseboat was to be made in steel ,  due to cost constraints we changed to plywood but I still wanted the conical bow that looks so good in steel . The first lamination of the Side Chines , Stringers and Gunwale's has been fitted  ,another is still to go and I have still have the bottom stringers to fit .

THE BEGINNING OF A DREAM

This blog will catalog the Construction of  " Jigsaw " , A 20 meter HouseBoat Catamaran that hopefully I will be able to retire on in my Latter Years . Construction is currently in progress using Fiberglass covered Dual skin Ply over Frame technique for boat construction .
Why " Jigsaw " , how else do you build a 20 m boat in a 6 m garage , Piece by Piece  of Course !!



Although designed as a Houseboat ,this vessel is well capable of Coastal Crusing  ,  1.2 meter wingdeck clearance , multiple watertight compartments and "Hull within a Hull"  Design allows for a greater range than your normal type houseboat and the strength to withstand the varied conditions it may encounter .

The Hulls are tied together with 5 primary bulkheads that transverse across the Main deck and Lock into the watertight structures within the hulls . Primary  accommodation is all above the  main Hulls   , these are only utilised as Storage and engineering area's but still have normal head clearance for good access . Main Deck consists of 2 Large Staterooms forward each with ensuite and 2 smaller staterooms aft of them with shared ammenities , aft of these are open sidedecks for external access and aft of this is a Workshop Area ( ManCave) .

Upper Deck consists of a Lounge area  , Kitchen  and Main Bridge with open areas either side of the Forward section .