Building A Proper Base

The job of the base in building an ENVIBOATS design is quite simple. Provide a large, stable platform on which to erect the jig.

My floor is quite true and level. Do I really need a base?

If it is very good, you probably don’t need to build a base. What we do in that case is simply lay Oriented Strand Board or “OSB” down to protect the floor from all the boatbuilding epoxy and “stuff”. It holds up well to screws for assembling your FasBilds. If any minor levelling needs to occur, you can do that between the OSB and the jig.

If you do need a base, we will be happy to provide a diagram and material list of the base with our kits. Just ask. It should be roughly the size of the maximum beam and the LOA (Length Overall). Take into account the standard sheathing size is 4’x8′. (If you are not in the US, you need to adjust to your sheet sizes) So, if you are building a 27′ boat, go ahead and make the base 28′ long as this is perfectly divisible by 4′. The base should consist of longitudinal members, transverse (crosswise) members and sheathing.  The longitudinal members should be doubled for two reasons. Length and strength. Standard construction dimensional lumber can be used for the structural components of the base.  The thickness of the structural member is always “2x” material.  The width (2×4, 2×6, 2×8, etc.) can vary depending on two factors:

1. The quality and “trueness” of the floor upon which the base sits
2. The size of the boat.

The quality and “trueness” of the floor upon which the base sits:  Basically, the question you are trying to answer is “How much shimming does it take to make the base perfectly flat.  If the floor is reasonably flat and simply not level, then 2×4 lumber should be sufficient for boats under 36 feet.  It might even be appropriate for bigger boats.  If, on the other hand, a great deal of shimming is required, then it is likely that heavier lumber (2×6, 2×8) should be used.  When in doubt, give us a call.  We will be happy to help you decide.  Remember, the base is the starting point for the quality of the boat.

The size of the boat:  For most of our boats, up to about 36′ LOA, 2×6 dimensional lumber should be an excellent choice for the structural members. Beyond that length, 2×8 lumber should be used. The joints should be staggered in the longitudinals in order to create the length required. The transverse members should be on 24″ centers. Typically, the transverse members will be trimmed in length so that the overall width of the base is divisible perfectly by 24″ increments. (Depending on the actual beam of the boat 12″ increments might also work.) When cutting the transverse members to length, don’t forget to take into consideration the width of 4 thicknesses of the longitudinals. (6″) It is usually easier and a bit stronger to put the base together with screws rather than nails.

Leveling the Base: It is vitally important that the base, upon which you setup your ENVIBOATS jig and build your boat is level and true. It is critical to level the frame or structure of the base prior to sheathing it with plywood (or OSB). Otherwise you will have a great deal of trouble removing the sag in the center of the base. Fundamentally, the process involves:

• Find the highest corner
• Bring the other corners up to that level
• Remove the sag from the middle of the base

There are several methods you can employ to level the base; each employing increasing levels of sophistication.They include:

• Water Level
• Laser Level
• Surveyor’s Transit

Water Level

Water will always seek level. Buy some thin clear plastic tubing. The proper length would be a bit longer that the length of two adjacent sides of your base. Most local Home Improvement Centers sell this tubing by the foot. You will also need some string. Fill an old one gallon milk jug with water and add a few drops of red food coloring to make it easy to see the level of water once you have it in the tube. Next, siphon water into the tube and, with a helper, begin by verifying which corner is the highest corner in the base. You do this by holding one end of the tube against the base on each corner and comparing the level of the water at the other end of the tube held against each other corner. Once you determine which corner of the base is the highest, shim every other corner to that level. Now use the string, stretched end to end of the base and corner to corner, and shim any sag out of the base.

Laser Level

Modern laser levels can greatly speed up the process.ONE WORD OF CAUTION: Never, under any circumstance, put yourself in a position where you might accidentally look into the laser.Use some scrap wood to make a few laser targets. A target might be two small pieces of 1×4 material tacked together at a right angle. Place them in various positions on the base such as one on each corner and one in the center. Train the laser so that it simultaneously hits each of the targets. Walk around the base with a tape measure checking distance from the top of the base to the laser line on the target. The corner with the shortest distance is the highest. Shim each corner and the center until the distance from the laser line to the base is equal on all targets.

Surveyor’s Transit.

There is not much point in explaining this method. If you own or have access to this expensive device, you know how to use it.

Once the base is level, ensure that the it is supported properly, in many places, (shims work well) to make it a solid platform and remove any springiness.

It is time to proceed to the next step!