Friday, 13 September 2013

Stern tube and support finished

After making some substantial holes in the hull for the stern tube it was time to epoxy/glue the keel underneath it and the tube itself into place.

First job was to glue up the keel underneath where the tube was to sit.  As you can see I used the threaded rod to put some clamping pressure on the keel.  I had sprayed them with silicon and thought I could get them out after.  DON'T DO THIS!  They are in there for the long term now and I had to get a spanner and wind each of the nuts all the way up and off.  They were to be permanently epoxied into the keel, just not this early.  I worked with them in place from then on and will have to all the way up the keel. 

Second job was to close off the stern tube from the inside so I could pour epoxy in from outside to fill up the gaps.

First behind frame 8.  I packed out around the tube with 25mm high by 20mm wide Hoop Pine left overs and a ply cover.  It was epoxied up first, and once dry was drilled for 14g x 30mm screws to go through the wood and up into the hull ply to hold it in place until the epoxy/glue set between it and the hull.  At the same time I coach screwed an extra hardwood cross piece across the frame to take the keel load and spread it a bit. May not have been needed but I cut out some of the original hardwood cross piece so why not!  After it dried I drilled the keel bolt holes down through it from on top.


And after:

Where the tube came through frame 8 and out over frame 7 I shaped some ply and packers (there was a gap you can see (below close up) where the ply of the frame did not go all the way to the hull at the top) and epoxy/glued and screwed it over the hole.  Thick epoxy/glue was pushed up over the top of the tube to seal up completely.

Before (bad shot earlier sorry):

After from a distance:

And close up:

Then I used lengths of 50mm x 50mm hardwood packing pieces to sit each side of the tube on the keel support to match the 150mm wide bit underneath.  After drilling holes and trimming the wood to length I epoxy/glued them in place.  A nice thick bed underneath the side pieces of wood means that later on I can fill the gap around the tube without the epoxy running out.

I did put a bit of epoxy in around the tube but it did not have glue powder in it so was very running and went out.  Concentrate on just having a thick layer under so you can tidy up the outside and have a good squeeze out on the inside beside the tube.  Last thing to do was to sit on top and pour normal epoxy down where the tube goes into the hull.  Because the inside was sealed, as it ran inside into the hollows I just kept topping it up slowly.  Leave a bit of time between as it runs in for the air to get out and keep topping up until it is full.

You can see the straight mixed epoxy on the right has hopefully filled all the support box (shown earlier) behind frame 8 and up to the top where the tube leaves the hull:

Whilst the epoxy was setting I used scrap nailed to the keel to help clamp down on the 50 x 50 wood each side.  I also placed a large piece of 150mm keel wood sitting across to hold that in place near where the tube went into the hull.  I used epoxy/glue powder to fill in where the tube leaves the end of the keel and a small amount down the other end near the tube/hull entry.  The remaining space will be filled when I finish the keel.

A final shot from the side, note the lighter scrap used to clamp onto:

Apart from gluing a bit down the front until it is level, the remainder of the keel will be build up 'dry' and then assembled/glued down once it is all ready.  Once level as close to the 3600mm full lengths will be used.

Next is to build up the front at the stem cap to level.

Friday, 6 September 2013

Keel hardwood and stern tube fitting

First thing to organise was the keel wood.  11 pieces of 150mm x 75mm kwila that were 3600 long.  These things were VERY heavy, craned off the truck but then carried in one at a time by me.  Hope the strong back lives up to its name!

I mentioned in the last post the stern tube I am fitting through the keel.  First step was to mark on the hull where the shaft line hit the hull using the drawings.  Then I started dry fitting pieces until the tube was supported from the hull to where the propeller will be.  From the inside I drilled up for the temporary threaded rod.

I used a piece of PVC pipe the same diameter as a guide as I carefully chiseled out a sloped hole through the glass/ply hull.  Once through and widened until the pipe fit (required inside and outside work so I didn't destroy the inside ply face)  I found it was going to pass through the hardwood cross piece on the bottom of frame 8.  Once I had made a start I drilled a 10mm hole through the hardwood using the sloped cut as a guide so I could work from both sides of the hardwood.  After much time and repeated climbing from inside to out and back again I could slide the 2000mm pipe up from the inside.

Below is a shot showing the slot in the hull as I pushed the tube out from the inside:

And an overhead shot showing the pipe lying (hopefully) on the centre line of the keel and into the hull:

A side shot of the same, my drilling of the holes was a bit angled and cramped inside of the frames.  If necessary I will cut off the rod as the keel gets higher and drive some drifts (I think they are called) from the top down as these rods will be permanently epoxied into the keel:

An inside shot from the side showing the path of the tube through the hardwood on frame 8.  It is probably not needed but because I have cut some of the cross piece out I am going to put an extra piece of hardwood across the centre line 300mm each side to spread the load from the bolts.  Basically epoxy/coach bolt a doubler of hardwood over the top:

And a slightly out of focus shot showing the engine end of the stern tube sitting over the top of frame 7:

Next is to build wooden supports on the inside of the hull where the pipe is located so when the whole thing is epoxy/glued in you can fill the whole lot up.  That will be in the next post along with epoxy/gluing the first bit of the keel in place first.