Strip planking, Transoms

Adjusting temps and rear bulkhead height

Posted by Paul

I have been experimenting over the last couple of days with the height of the rear bulkhead. I am having a cross between a walkthrough and non walkthrough and neither fully suits so I am experimenting until I get the height I need to accommodate the outboard, still have a raised duckboard and still have a reasonable angle on the rise of the steps. I also have another idea (actually it is James idea) for the seal of the outboard hole in the hull when the outboard is raised which requires a little extra clearance of the outboard at the hull hence the need for more height in the outboard compartment but more on that later.

Because I want a little more height in the outboard chamber, I have raised the height of the transom. I had to raise the height anyway because it is currently cut for the walkthrough, and the non walk through height is the height of the section with the curve on the current bulkhead. But the non walkthrough does not have a duckboard and to complicate matters further I want to raise the duckboard to the height of the seats so that the area below will be a full length locker for non collapsible things such as fishing rods, boat hooks, gaffs etc. and at that height my centre walk through will be at seat height so you walk through from the duckboard to the seat top and step down into the cockpit. This additional height meant that the steps have to reach that height first or otherwise I will need to have another set of steps on the duckboard and I want to avoid that but that meant the steps will need to be higher and steeper. It is not higher by much, only about 150mm but it needs to be thought through properly first.

Once I had decided on the height of the rear transom, and this was pretty much dictated by the height I felt I needed for the outboard (probably a 30hp 4 stroke) I trimmed the section I will glue into that space to the size I had marked. As it is higher I have also made the radius of the turn a little larger. I will use this piece as a stencil for the other hull then glue it into the space ready to plank. I have also run a temporary stringer across the bottom bulkhead and plank to it, to the centreline and then cut it away when I am shaping the stairs. Once I had put the bulkhead add on back in place I then made a little mistake in the set up of the last 2 temp bulkheads. No big deal and a great learning experience but it did eat up some time.

What I did was work out the height difference between the 2 bulkheads then I split the fall between them into 3 so I could work out the height of the 2 temp bulkheads evening out the fall. Mistake. An even fall results in a flat line not a curved one. I realised this the moment I put the batten on to see how the fall looked. The rest of the boat curves and here is a flat slope. It didn’t look right from the first glance. An experienced boat builder would see this in their mind before setting out the bulkheads but to my credit I saw it straight away once I had a visual.

James gave me a hint. He suggested I attach a long batten around the middle of the hull length and attach it to the rear most bulkhead and pull it down to the permanent bulkhead 6 (saloon bulkhead) and then move the temps up to meet the natural curve that will be in the batten. That’s what I did and the pics above demonstrate the difference in height and the more pleasing curve that it presents. The added height is also an added bonus in extra interior headroom. I will have a slightly better headroom in the rear of my hulls compared to either of the other options. I will have a slightly higher waistline of the cockpit but we are talking 100mm so it is negligible from the outside but 100mm from the inside (added headroom) is quite significant and will make my idea of where I put the shower work really well. More on this when it comes to internal fit out.

So everything worked out really well, the changes make some of my future changes all the more workable and will still look really sleek and practical. I experimented with step rises but I still don’t have it quite right yet. The step profile in the picture does not leave me enough height for the outboard, but I will get that right with a bit more experimenting with cardboard cut outs.

So now I have finally set the temp bulkheads in place I can start stripping the Duracore and start on the dry planking. And along the way I also want to finish the forebeam.
There has also been a considerable visual change to Nine Lives over the past few days. The forebeam has been made and fitted, the last of the bridgedeck panels glued in and the saloon turret formed and most of the deck panels are also glued on.

nine lives beamnine lives beam2nine lives bridgedeck finishednine lives saloon 2

nine lives saloonnine lives james fitting saloon sidesnine lives saloon 3nine lives logo

You May Also Like