offsets question atkins shoals runner

Hi, I am new to boatbuilding and to this forum. I have the plans for Atkins Shoals Runner and have some questions about the offsets. This boat has a flat keel planked with 1 1/4 " white oak. On the offsets the "base to keel" measurements do not seem to match the bottom of the keel on the profile drawings. If you use the "base to keel" measurements to mean the bottom of the keel and the " rabbet above bottom of keel" to locate the rabbet line and draw the body plan accordingly the result clearly does not match the lines drawing. Could the "base to keel" mean something other than the bottom of the keel? If there are any designers or builders who have experience with Mr Atkins designs any information would be welcome.
Sorry for the longwinded post.

 

I suspect Billy was a "base line" guy. This means the first line he drew was a horizontal line at the bottom of the profile drawing. He then erected perpendiculars to this for his stations. Typically a base line drawing will have all the "heights" up from this base line. Check your "lines" drawing and see if the base line is present.

Those seabright models of his have some rocker in the keel plank, so this line will not be a straight line, though much of the after portions may well be.

Establish your base line as you begin lofting, making all heights measurements from there, for your old style torpedo stern, shallows master.

 

Thank you for responding, PAR. You are correct, the offsets are from the base line, but the question is could the "base to keel" phrase mean something other than the measurement from the base line to the bottom of the keel, such as the planking at the keel or the rabbet line at the keel. If you scale the profile plan the measurements from the offsets seem to indicate the rabbet line.

The keel is straight from station 1 to station 10 with a 1 degree angle sloping aft. Again this is the "base to keel" offset dimensions.

I am concerned about getting this exactly correct as this effects how the hull form forward transitions to the tunnel stern aft.

I am interested in getting some professional advice on several details of this project; adhesives, small changes to deck layout, materials substitution, etc.
Maybe you would be interested or could recommend someone familiar with Mr Atkins designs or older designs in general. Any information would be welcome.

 

It's difficult to tell without seeing the plans, but my sketch of the profile shows the LWL parallel to the base line. I'm not sure what Billy means with that phrase, though his plans are usually easy enough to read.

Do a scale lofting, say 1":1' an check the "base to keel" heights and see if they do hit the rabbit. It seems unlikely he wouldn't have a rabbit height, but chose to loft to the bottom of the keel. Typically the keel would be dimensioned off the rabbit, again with heights (negative below the rabbit, positive above). This is often done with "pull outs" or small diagrams which show the relationship of the keel bottom to the rabbit.

Drop me an email (click on my name) and we'll see what we can work out. Considering the age of the plans, you're wise to seek advice on some "modern" material substitutions, ditto for adhesives and equipment/hardware.

 

In my research about the Atkins Rescue Minor and Patsy models some of the builders who completed the project and posted about their effort/experience, stated that there was not enough information in the plans to complete the aft sections.

The link below is one example. This may not be true for your model, but the hull form is so similar.


www.douglasbrooksboatbuilding.com/rescue.html

 

Hi Jetpak,
I have looked at most of the photos of "Rescue Minor" available on the web and they all seem to have slight variations on how the "tunnel" develops and in the shape of the "tunnel" itself, some flatter, some more concave, etc. The plans must leave a lot to the individual builders descretion/preferences as you suggest. The plans for Shoals Runner seem well defined in this area, however, with good detail. It's early days yet, though and I have run into a problem with the keel profile/ depths on the offsets. It's probably my inexperience interpreting the meaning of the offset table that is the problem. I have enlisted the aid of an experienced designer on the project and have confidence I will be back on track with the lofting in short order. Thanks for the info.
Randallg

 

Shoals Runner offsets

Everything seems to be in order to me.But you do have to look around a bit. BASE LINE to L W L is 8 1/4". BASE LINE to KEEL is a bit harder. Station O is given as 8 1/2", station 1 is 4 1/8", then the fun part, a straight line to station 10 that is given as 2 1/2". For stations 2 through 9 what I got in order is :#2-3.944445",#3-3.763889",#4-3.5833335",#5-3.402778",#6-3.2222225",#7-3.041667",#8-2.8611115",#9-2.680556" or draw a line on the floor, Pull a string.
Round off to as close as you want to work. I did find some small mistakes mostly in the L.W.L. breadths,no big deal. I am reworking the plans.You may want to look over some plans for SEABRIGHT SKIFS , EVERHOPE, RESCUE MINOR, LITTLE WATER, and some of the Pen Yan boats.