PLANS

[Greg Davis]

The term Mackinaw Boat indeed seems to apply to a variety of different small craft used on the Great Lakes. Chapelle discusses them along with sample drawings in his American Small Sailing Craft book. One of the more well documented variants goes by the name of “Collingwood Skiff.” Check out back issues in WoodenBoat magazine. They have had a number of articles.

Roger

I experimented with the plans / table of offsets that Chapelle took off a half model of 'Mackinaw Boat - Lake Michigan type of about 1881'. But now I am heavily leaning toward using the plans of 'Wabesi':



I've also got table of offsets, body/ half breath / sheer / sail plans as redrawn by Roger Swanson. Rog

 

[DARIVS ARCHITECTVS]

More basic terms to know:

 

[Dart]

Length overall (loa): and Length on the waterline (lwl):

The 95ft 6 in is the LOA measurement and the red line is the LWL

Dictionary of American Naval Fighting Ships list the length of Naval ships at the LWL Admiralty drawings may record the length on deck or between perpendiculars. Then even between perpendiculars breaks down into overall and from the back of the stem to the front of the stern post. Then we have the add measurements which calculates the cargo capacity and cargo weight a ship can carry.
View attachment 555313

Could it be like this? Up to the tongue and groove (red). Up to the turntable (blue).

 

[Roger Pellett]

There are “Official” and unofficial lengths to describe the length of a ship or boat.

Official:

LBP- Length Between Perpendiculars. This is usually found on the Naval Architect’s lines drawing. Though not designated on the drawing above it would be approximately the same as the length of the Red Line above.

Load Waterline- As the name implies this is the length of the waterline at which the Naval Architect’s intended the vessel to float. In the case of a vessel like Gracie S. it would be measured with the vessel ready for sea; loaded with fuel and stores.

Commercial cargo carrying vessels are also governed by freeboard regulations. Freeboard is the vertical distance between the vessel’s weather deck and the water. This is marked at the waterline by the well known Plimsoll mark and differs depending on the situation; Summer, Winter, Fresh Water, etc. For these vessels, waterline length is measured at the summer load line.

Register Length- This is a legal measurement to establish Tonnage. Tonnage is supposed to be a measurement of the vessel internal volume that can carry cargo. It is NOT a measurement of Weight. It can be found in descriptions of vessels daring back to the 1500’s when one “Tun” was assumed to occupy 100 cu ft of cargo space. Like everything else in life its calculation has become musc more complex over time. The length used to measure it is similar to, but not necessarily the same as LBP. It has no application to ship model building EXCEPT researchers will find it used in Ship Registers (like Lloyds) and Customs House descriptions.

Unofficial:

Length Overall- Usually the longer blue line shown in Kurt’s post above but depends on the situation. Selling a boat, advertise it to be as long as possible, Haggling with the marina or harbor master over docking fees, keep it short.

Roger

 

[AllanKP69]

More basic terms to know

You point out frame lines, but I wonder, are they frame lines or station lines? They line up in the forward frame of each pair, but not in the exact same place for each pair. If they were frame lines wouldn't it be better if they lined up in the middle of the pair or perhaps the leading edge or after edge? The center to center distance of the double frames is 25.44" but the center to center of the body plan lines is 26.05" Then again, perhaps, one or both of the drawings are not correct. I enlarged these to full scale, but if the 1:48 drawings are not accurate, enlarging them is not meaningful. At 1:48 it is not a huge thing, but something is amiss, be it the drawings are not accurate or they are, but there is no relationship between the station lines and the location of the frames.
Allan

 

[Roger Pellett]

Yes, they are probably station lines. In preparing a lines drawing, the Naval architect spaces station lines to best describe the shape of the hull. As this lines drawing would be redrawn full size by the mould loft, orientation of the frames could be determined then. The table of offsets sent to the mould loft would include a note specifying frame spacing to meet the Naval Architect’s structural requirements.

I realize that there were conventions in places like Royal Navy dock yards where lines drawing stations represented some fixed multiple of frame spacing.

Roger

 

[Greg Davis]

Then again, perhaps, one or both of the drawings are not correct.

For shaping my solid hull I am relying primarily on Sheet 1, and using the Inboard Profile as secondary. For interior aspects, I'm making use of the Interior Profile and the Beam Plan.

 

[DAWarden-(Jaager)]

Here is an abridged version of the lofting from my proposed log:
Painter would not open the TIFF. I went to PS in the cloud and cropped the lines sheet into three sections and saved them as PNG (lossless format)
I did the same for section 14 and inboard profile.

OPEN Profile.png
it is Huge! enlarge canvas if necessary
Adjust orientation - compare a station to base - duplicate layer - ROTATE - trial -fail - delete layer - duplicate new - test repeat until the orientation is correct
Check plan scale to 1:48 ruler 10' = 19.25' - duplicate layer - SCALE with estimated values - turns out that 51.9% produces 10'=10'
Add a legend layer identifying each station with its number

OPEN Body.png
SCALE a duplicate adjust 51.9%
ROTATE to match baseline
CUT background
Body delineates the station numbering.

The profile has no information about the decks.

OPEN inboard profile.png
ROTATE to match baseline - check scale SCALE to 1:48 - CUT background - overlay profile 48
I am guessing that the deck locations are at the keel/midline.
In section 0 the cockpit deck is horizontal.
In section 14 the cabin deck is horizontal -
the deck has a roundup

OPEN roundup.png (section 14) ROTATE to match baseline - check scale SCALE to 1:48 - CUT background
Measure the roundup of the deck beam = 3.5"
Move deck layer1 down 3.5"

Reading this - something comes to me:
My station/frame patterns have the location of the rail, LWL, rabbet, and top of deck beam at side. (GracieS has no gunports so no sill or lentel. No wales either.)
By dropping the deck 3.5" along its whole length I have made each beam have the same crown height. I am going to have to figure a fudge factor to get the height of beam at side going higher as it progresses to the bow and stern.

This is a long way of saying that each TIFF was a different scale and had its own rotation. Since Profile, Body, WL are all on the same sheet, the rotation and scale are the same. All of the stations have the same interval. I use them as being the midline of every other bend. I found no strangeness with the plans.

 

[DARIVS ARCHITECTVS]

You point out frame lines, but I wonder, are they frame lines or station lines? They line up in the forward frame of each pair, but not in the exact same place for each pair. If they were frame lines wouldn't it be better if they lined up in the middle of the pair or perhaps the leading edge or after edge? The center to center distance of the double frames is 25.44" but the center to center of the body plan lines is 26.05" Then again, perhaps, one or both of the drawings are not correct. I enlarged these to full scale, but if the 1:48 drawings are not accurate, enlarging them is not meaningful. At 1:48 it is not a huge thing, but something is amiss, be it the drawings are not accurate or they are, but there is no relationship between the station lines and the location of the frames.
Allan

View attachment 557225

Yup. Station lines. I guess frame lines would be, naturally, on the frames.