Sea Sled madness. It’s in my brain.

Righty ho, will do - I have taken the liberty of re-posting my sketch above on the jib crane thread.
Help designing simple jib crane https://www.boatdesign.net/threads/help-designing-simple-jib-crane.65504/page-2

 

19 months later, I couldn't resist a reply to your original post - if only to help illustrate how far you have come with this amazing build over the past 19 months.
And (even more) amazingly, you have not run out of steam - far from it!
If anything, you are turbocharged now! Go for it!
You have a huge following on here - you just need to 'do a Tally Ho Leo', and start that YouTube channel re Serenity the Sea Sled.
And if it takes off.... well, maybe then you don't have to worry about the cost of the new engines.

 

Martin, you hit the nail-on-the-head there my friend.

Leo is a very clever boy; I've watched his every video.

John is on a mission and he's a good man for it.

Dogspeed brother!

 

From the crane thread, but build thread relevant.

Here is the sketch. To scale, within reason: 1 square = 30cm/1'. The gantry is hinged on the side decks over bulkhead 1. I have not shown the blocks and tackle controlling the position of the gantry. In this sketch I drew the gantry 8' high, because standard dimensional lumber, but 10' high is hardly any heavier, and gives more clearance and reach.

 

DG my thoughts too, spreads the load evenly through your gunnels, winch on stern to lift may need mounted with some height.To lift out winch mounted to a solid point ahead of bow.
You will just have to load with bow to wharf or probably better at ramp with load in back of Ute/truck.

 

Add one thing steel structure will be much lighter than swiveling crane and with made interchangeable pipe uprights universal joints on the mounted pivot point, you could load taller /wider cargo ( within reason)

 

My offsets from my original drawings, a year and a half ago. Some things half changed. I'll post the as built values in mm after this...

"So I made some assumptions, copied some forms, and read some papers. Savitski comes to mind. There are others.

I’m out of practice here, so I may have chosen unconventional reference points. Please bear with me.
There are 4 curves described here.
-Tunnel, where the value given is the height of the apex of the inverted v, at each station, above the floor the boat rests on.
-Keel, which are the two parallel chines that define the bottom edge of the tunnel. They take the form of the rails of a sled, hence Hickman’s choice of the term, 105 years ago. They are absolutely parallel planes, 8’ apart.
Chine, which in this context is the chine that defines the transition from the topside to the non-tripping chine. Chines are defined by their deadrise and length at each station. Obviously they, unlike keel and tunnel, don’t stay parallel to the centreline.
Sheer is dead level at 56.75” for the full length of the boat. Ugly,I know. But functional.
There is a station off normal spacing, 84”, where the keel leaves 0” and starts to curve up towards the bow, and sheer leaves 60” from CL and starts to curve in to the bow. I call this rollup for obvious reasons.
There is a flat surface at the bow, like a bumper on a car, which I am calling the Ram. It forms a landing point for the various curves. It’s dead flat, just over 8’ wide and 8 3/4” tall. Port and starboard ends match the angle of the topsides. A solid beam to push against a rough cliff face and land labourers in an unprepared spot.

LOA is 25’. Beam is 10’ at the transom, and at the sheer from transom to rollup station. Station spacing is 30”, or 10% of loa, except at rollup.

Please forgive the use of imperial measurements. My brain is damaged by the proximity of the USA. Also, I apologize for the awkward format. I’m working on an IPad, and I hate the thing.

Tunnel @
Ram 48”, S1 33.875, S2 24.75, rollup 17.375, S3 15.8125, S4 10.5, S5 7.94, S6 6.375, S7 4.94, S8 3,25, S9 1.7, Transom 0”
Keel @
Ram 48”, S1 13.375, S2 1.56, rollup and aft 0”
Chine @
Ram na, S1 9.125” 79deg, S2 12.75 44deg, Rollup 13.25” 36deg, all stations aft of rollup 13.25” smooth curve to transom @25deg
Sheer@
Ram 49.75”, S1 56.375, S2 59.25, rollup 60”

Remarkable to think that this tiny group of numbers represents hundreds of hours of study and labor.

John"

 

Station spacing 762mm except @ 10
Values:

1118, 860, 629, 402, 267, 202, 162, 125, 83, 43, 0

1118, 340, 32, 000000

NA, 232, 337

NA, 79, 52,..., 25

1264, 1432, 1505, 1524

Some of these will be off slightly. The method of strip planking served as an infallible batten, and occasionally required an adjustment of a few mm.

John

 

Can anyone make sense of this, or not make sense of this?

 

It makes sense to me but I had to review the previous 2 or 3 posts.

Keeping in mind that this is the world wide web, English is not everyone's first language,
you may want to make it a bit more "user friendly".

You posted these for Ad Hoc, no?

 

Please correct me if I am wrong here.
So we have HT is the height of the tunnel above the baseline at each station on the hull centreline
HK is the height of the chine above the baseline at each station
B is the half breadth at each station of the sheerline and the chine (as the hull sides are vertical along the whole length (?)
Re your 'NA', is this the CentreLine of the vessel? I am not too sure what the NA numbers are for (are they vertical or horizontal offsets from the NA or centreline?)

John, how about putting these numbers into a spreadsheet (can spreadsheets be attached here? I hope so) - then it might all be a bit more logical.

 

I can see the confusion.

Whilst one could redraw the lines based upon the numbers posted, it is not in standard format. For example, noting the angle and the length of the angled facet, may be ok, if you're doing this on a drawing board/scrive board/computer.... but when plugging data into a stability software, the end points, their relative X and Y coords from the baseline and CL are required.
Since for each station, I would have to draw (measure) or calculate the X and Y coord from the 2 datums for the point shown here:

 

Ah. Ok. I'll do that

Ok. I'll reformat.

 

John,
Did you survive the heat snap?
Kinda slows production, 'eh.
Dogspeed brother!