We had one of the annual chats about "what to do to make this boat better" at Cobnor this year. In the absence of Wayne again (where are you mate?), focus turned to MilliBee's trailer.
Everyone agreed arms are good, roughly 3/4 towards the stern. MilliBee's central bulkhead is the widest, deepest part of her. So I measured the angles and lengths from the plans and built a prototype arm to retain her in a blow but also to limit the hull rolling:
Note also the nice blue mudguard(s). Totally legal Ratcatcher! Red-White-Blue, Marie Le Penne would be so proud.
I had originally thought a dog-leg joint would be fine. But it became obvious that extending the top arm to form a triangle would be much stronger.
The inner arm is to stop the boat rolling.
A red LED on the back and white LED on the front will make the arms legal at night, as they will become the widest part of the trailer.
Finally I found keel rollers 200mm and 300mm wide are available on Ebay. At the back a wider roller could be lower and 6 degree ply sides will just clear the widest part of the boat. Also it prevents knocking the bow on the metal frame and should guide the bow towards the roller.
My old yacht trailer dolly had four arms, made from alloy scaffold poles covered with rubber hose. They made getting the deep-keel boat lined up with the submerged dolly a great deal easier. I had marks on the gunwales that lined up with two of the arms, so I knew when the boat was sitting in the right place on the dolly, several feet below the water's surface. Once lined up I'd secure the boat to the dolly arms to keep her in place.
As I only used the dolly twice a year, on the old seaplane slip at Loch Ryan, I would let the tide going out settle the boat down when recovering her in the Autumn, then winch the dolly up and on to a break-back trailer fitted with rails for the dolly wheels (which were cast iron things, scrounged from a naval dockyard).
The main advantage of the arms, apart from marking the dolly position, was that they stopped the boat drifting off to the side and allowed the keel to settle into the U section down the centre. Having used a trailer with arms like this. if I ever had a fairly deep hulled boat again I don't think I'd want to go back to a trailer without them.
Good work there Paulie,
Those are very nice mudguards.
You could probably saw a foot off the top of those arms and they'd still do the job, don't forget to leave enough room to get some pipe insulation round them to prevent chaffing.
No one likes chaffing.
A cracking job Paul. Many thanks for putting me in the same paragraph as "Marie le Penn", an honour not often bestowed upon us simple Ratcatchers. Yes, she would be proud, BUT only when you had infilled the tri-angle between the chassis and the leading outside edge of the mudguards in order to comply with her countries requirements. And keep the weight down as an HGV examiner would frown on the forward protruding studs.
Thanks for the praise; they do look good don't they. I had a patriotic desire for red, white and blue, probably due to the Spitfire flying around Cobnor last month. Also the Guardian conspiracy theory that 'Theresa Won't' until Marie La Penn has stoked the Frexit fire during the French election in the spring of 2017.
And keep the weight down as an HGV examiner would frown on the forward protruding studs.
The studs are round headed cap screws, which offer a smooth surface to the tyre during a fender bender.
T'other way round the bolt might cut into the tyre - a blow-out at speed could be nasty. Smug grin
Gather some scrap block wood and the metal ends of a computer table:
Cut the main frame cross section into the wood, cut a slot for the keel. Then trim the metal frame to a T shape:
The T-shapes fits snugly into the trailer box section, which has convenient holes and hand clamp bolts:
Finally the wood cross section can fix to the T shapes:
I've studied the launch and recovery for years. The starting point is the rear keel roller just at water level. The wooden cross section will guide the bow onto the keel roller and prevent it bumping into metal.
The winch force will twist the boat about the keel slot, forcing it to align with the trailer. The cross section will start to support the hull when the first few feet are on the trailer, preventing it rocking sideways and keeping the keel aligned on the roller(s).
Docking arms can bolt to the wooden cross section, which will be bolted to the metal T shapes. I think arms that support just the chine panel at 45 degrees maybe enough to keep the hull aligned in waves/tide/wind.
The wood will be carpeted of course, but recycled plastic might give it a slippery surface.