Reference Points for Dimensions

[76SeaRay]

As I am replacing the transom, stringers and floor, I want to make sure and get everything true and aligned. I may be over thinking this but how does everyone determine a reference point for all measurements. For example, do you run a straight edge across the gunwales and measure down to points on the stringers, motor mounts, and floor? Do you level the boat and establish a level line across the gunwales or floor from which to measure? In determining the vertical centerline for the outdrive keyhole, do you measure from side to side at the top of the transom, measure side to side near the bottom of the transom and then draw a vertical line through the mid points of the two measurements? Or, do you level the boat and drop a plumb line from the top of the transom so that the plumb line passes through the center of the low point of the hull below the outdrive (essentially the center of the drain hole under where the outdrive will mount)?

Lastly, is it all that critical??

 

[chevymaher]

Myself I went by the old decking. Even once it is ground it is obvious where the deck was. I ran 2 chalk lines front to back Where the stringers would be. I made the bulkheads and installed them. Then used them as constants for all my measurements.

 

[Grub54891]

Before, during, and after teardown, I documented measurements. When setting up to check it all over, I laid the fuel tank in, ran string lines across, and stem to stern. Double checked everything and marked height, allowing for deck thickness and stringer height, all the fun stuff.

 

[76SeaRay]

That looks great. So, you measured in reference to the wall base on both sides for height. Why the spacer blocks on each string line? Is that string the top of your floor?

 

[Grub54891]

Yes, I put the wood blocks in and adjusted the height till I got it to where it had to be. Then marked the hull with a sharpie for reference. The reason I put the tank in was to make sure the deck would clear it, then measured the string height as to make sure the stringers were the right height, allowing for floor thickness. Worked out pretty well.

 

[gm280]

Most people I see on here, including myself, used the center line setup to get everything dimensioned from that point. Check out some of the project boats on these forums and see how they did theirs. Being how a boat doesn't have square walls and such, it gets interesting to get started until you see it really isn't hard at all once to get used to it. But center hull line is the typical setup in most rebuilds. JMHO

 

[76SeaRay]

Nice looking stringer work in your boat. For my old floor, the plywood flooring sits right on the hull bottom at the base of the wall unlike yours that seems to sit and inch or two off the hull bottom at the base of the walls. But, it appears that the joint at the bottom of the wall may be the best place to use as a reference. From there, I could level the boat front to back and side to side using the strings then use a laser level to establish other locations until the new floor is installed. My old floor has a little bow in it on each side and looks like the expanding foam at the factory pushed it up a bit or swelling from when it was wet. So, I think it isn't the best reference and better to start with the clean hull bottom I think and design the measurements from the base of the wall and fuel tank like you did instead of measuring and trying to recreate the old floor.

Again, I am probably trying to be way more accurate than I need to be, but, isn’t that part of the fun in doing the job right………

 

[Mad Props]

I did what chevymaher did... basically kept the lip of the old deck in until the stringers and bulkheads were installed, then i ground out the old deck and took measurements from the centerline of the boat to each side on the hull using a long straight edge resting on the tops of the stringers to get measurements for the deck..

The important point is, it doesn't matter if your boat goes back together with a slight curve to the left... a inch or so different here or there isn't going to be noticeable.

 

[Grub54891]

I also had to reference the front of the bow, as the floor runs under the walkway. Had to make sure the height was correct, to match the bow area. After laying the rear deck in, I decapitated the boat to finish the bow area.