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Frequently Asked Questions [FAQ]

NOTE: Many other answers are available in our HOWTOs and Tutorials.

Boat types

I hesitate between boat Y and Z, can you help me?

We can not choose a boat for you but here are some tips:
- Read the study plans page for each boat. Most questions are answered there.
- If you hesitate between hull types or materials, see some books about yacht design. We are constantly adding new information to our web site but it will never replace excellent books like "Understanding Yacht Design" by Ted Brewer.
- See our message board: some of our builders write about their experiences and we answer many questions there.
- If the selection is too confusing, reconsider your requirements. Your program may not be clearly defined or your expectations may be too high for one boat.

What is the capacity of the XYZ boat?

Safe capacity varies with many factors: the size of the crew members, their experience, the weather, the conditions in which the boat is used etc. For example, in good weather, an experienced crew of three or four can safely use our D4 in dinghy service but a pair of inexperienced heavy weights will be in danger in the same conditions.
Our study plans specify what we consider to be the capacity under average conditions. Ultimately, the skipper must decide what is safe capacity considering all of the above.
We help you in specifying the PPI for some of our small boats: this means the Pounds Per Inch of Immersion. In other words, how many lbs. it takes to bring the waterline up one inch at the designed displacement.
Another good way to estimate capacity is to take the main dimensions listed on our web pages and trace an approximate outline of the boat on the floor. Imagine your crew in that space.
For outboard powered boats, we use the USCG capacity calculations and usually announce a lower figure to be safe. BTW, there is no requirement for a capacity tag for a home built boat and there is no USCG capacity tag requirement or standard calculation for sailboats.

Do you have plans for a house boat or tug boat or Sea Sled or . . .

All our stock plans are listed at our web site but we have many other ones in the works. Some are well proven existing designs that we will adapt to amateur boat building, others are new projects.
Post a request for a new design on our message board or at
If there are sufficient requests for a certain type of plan, we may design it.

What is the difference between the bateau plans and others?

We design composite boats that use plywood, not fiberglassed plywood boats.
The difference is important: the structure and assembly method of our boats are similar to fiberglass boats, not wooden boats.
The advantages are stronger and lighter boats that are easier to build, last longer and perform better.
Most other plans for "stitch and glue" are simply plywood boats glued together with some glass and resin. In our boats, the glass and resin are the most important parts.
All our larger boat hulls, 15' and above, are made of a composite sandwich. Either plywood or foam between layers of directional fiberglass.

Can I build boat XYZ in aluminum?

Most of our boats can be built in Aluminum. The general structure will be identical and all the dimensions from the plans can be used. The weight of an aluminum boat will be very close to our plywood composite hull weight. The developable hull panels can be cut in aluminum directly from our plans. However, we will not specify plate thickness and required stiffeners. If you contemplate the building of an aluminum boat, you should be familiar with those requirements. For plating, you should use alloys such as 5052 or 5086, for extrusions, 6061 or 6063.


What is the difference between our building material and others?

Everybody understands the difference between fiberglass and plywood or between traditional wooden boat building and stitch and glue but what makes our material unique is not always well understood.
Let's look at three different materials and construction methods:

  • Plywood on frame
  • Stitch and glue
  • Plywood cored composite

Plywood on frame is a boat building method that appeared before WWII: a boat made from plywood panels fastened and glued to a wooden frame.
The frame is made of solid or laminated wood. That framing is the skeleton of the boat and supports most of the loads.
It is made of a large number of parts that must be beveled and fit precisely together.
Those parts are assembled with a combination of mechanical fasteners (screws or boat nails) and glue.
The framing is then covered with plywood panels. Long panels are made from scarfed plywood.
In some cases, the finished hulls are covered with fiberglass for resistance to abrasion and to seal all the small gaps.

The structure made from a large number of parts will not last as long as a one piece composite hull.
Plywood on frame requires good woodworking skills. We do not design for plywood on frame.

Stitch and glue appeared in the 1950's. The consensus is that the first stitch and glue boat was the Dinghy Mirror. The boat was made from plywood panels assembled with fiberglass tape and polyester resin.
Over the years, cheap but unreliable polyester was replaced with epoxy resin.
Epoxy is all together a glue and a laminating resin. The epoxy bond is stronger than the plywood itself.
A stitch and glue hull should be a one piece structure (monocoque) but many designers lack trust in the material or the knowledge to design a fiberglass structure. Often, the fiberglass tape is used only as a seam between panels but wood is still used for structural parts like keels, chines and bow stems. Those boats are hybrids between stitch and glue and ply on frame.
A few designers produce plans for stitch and glue boats engineered like fiberglass boats.
The hulls are made of plywood panels welded together with fiberglass and resin. No solid wood is used.
Just as in a production fiberglass boat, the framing is made of fiberglass beams. With decks and soles integral to the hull, this produces a true monocoque structure stronger than their fiberglass counterparts.
Not only is stitch and glue light, stiff and strong but it is builder friendly.
No exact fit between parts is required, epoxy is gap filling. Gaps between parts are recommended in all text books about composites. This is the opposite of wooden boat building but works in favor of the amateur builder.
Stitch and glue is ideal for small boats less than 15'.
Some designers produce plans for stitch and glue boats up to 45'. They use thick hull panels laminated from several layers of plywood. We prefer to use more fiberglass as in our plywood cored composite boats.

Plywood cored composite can be considered advanced stitch and glue.
The building material may look similar to first generation stitch and glue but while the framing is identical, the hull skin is different.
In plywood cored composites, the panels are a true composite sandwich.
Just as in high tech boat building, the panels are made of a core between two skins of fiberglass. Those fiberglass skins can be quite thick.
Our composite uses plywood as a core instead of foam or honey comb.
It has many advantages for the amateur or custom boat builder.
The hull is assembled just like a stitch and glue hull. There is no need for a male jig: thanks to the stiffness of the plywood core, one can often use the frames and bulkheads as a jig. In some cases the builder can use a basket mold.
The thinner plywood panels are easy to bend and the final product is truly a fiberglass boat without the risk of blisters associated with polyester.
The materials are easy to find and familiar to the amateur but the final product is an high tech boat usually lighter but much stronger than a production fiberglass boat of the same size.
Plywood cored composite is ideal for boats between 15 and 30'.
From plywood cored composite to foam sandwich, the transition is easy.
The building sequence is similar and only the core material changes. Foam sandwich requires a different type of mold and much thicker fiberglass skins than plywood cored composite.
Around 28' , at equal strength, a foam sandwich boat begins to be lighter but it cost more in labor and material, approximately two times more.

How do I make long plywood panels?

We use standard sized plywood sheets only. This means 4' by 8' (122 by 244 cm). Long panels are made by assembling short peices with butt blocks or fiberglass splices. See the Building - Basic section for details.

What is the precision required when cutting panels?

Not much.
There are two factors to consider.
1. Epoxy does not require tight fits, quite the opposite. Some gap between parts is required for the epoxy glue to work.
2. We want to avoid hard spots between panels. The strength comes from the fiberglass and a gap is preferred.
For those reasons, 1/4" precision (5 mm) is more than sufficient. Our plans are very precise but the dimensions use a 1/8" (3 mm) tolerance.
Do not try to be more precise, instead focus on fairness and symmetry when scribing and cutting parts.

Which type of skills are required? Woodworking?

90% of our plans are for "stitch and glue", the easiest boat building method that ever existed. No woodworking skills or special tools are required: see the pictures in our tutorials. You must use fiberglass and resin, something you can learn in one hour with our trial kit. There is never any lofting with our plans: we did the lofting for you. All dimensions are given for parts such as side panels and frames: you can cut them flat on the floor. No need to make patterns from a jig! For all small boats, we also supply paper patterns. Builders of larger boats prefer to scribe the outline of the panels from the dimensions: it is more accurate. We always show details like the ideal nesting of the plywood parts on standard plywood panels. All plans are sold with building notes. Altogether, our plans are very detailed and easy to build from.

What is stitch and glue?

Please read our How To files and look for the Stitch and Glue Primer. Our building method and materials are very different from wooden boat building. The strength of our structures relies on the fiberglass and resin, not on wood assemblies. Our keels, chines, bows, frames etc. are all made of fiberglass, not wood. Gaps between wood parts are preferred to a tight fit. See our tutorials: building strong and clean fiberglass laminations is easy. Our hull shapes are defined by the hull panels, not the framing or the jig as in wooden boats. This means that there is no lofting and that jigs often not required. All panel dimensions are precisely calculated for you. Plans and assembly methods are conceived with two top priorities: ease of building and strength. We do not use scarfs, there are no bevels, no need for special tools. Read our How To files, check the pictures. Visit our builder’s web sites, many describe the building of their boat step by step.

What is an epoxy fillet?

An epoxy fillet is a rounded bead of epoxy putty between two plywood parts. The putty is epoxy thickened with silica or microballoons or wood flour. The fillet does two important things. First, it is a structural joint between two parts. Second, the filet creates a rounded corner so that the fiberglass layed over the top of the filet makes a smooth corner bend with no air bubbles. The radius of the fillet is equal too or larger than the maximum bending radius of the glass that will cover the fillet, in general ?”. When done correctly, the two panels, the fillet, and the fiberglass tape become one solid fused component that structurally reinforces the boat. Those taped seams are the true chines, keels and framing of our boats just as in production fiberglass hulls. Those taped seams can be very thick: close to 1” in some cases. Our builders use many techniques to create clean fillets: squirting the filet material out a plastic bag like a pastry piping bag, shaping the filet with tongue depressors, PVC pipes, small plastic spoons etc. See their web sites for pictures.

What is a fiberglass seam?

A fiberglass seam is fiberglass tape joining two parts of the boat. Structural seams are made of biaxial tape, sometimes many layers with offset egdes. Thick fiberglass seams become structural stiffeners like chines or keels. Less important seams can be made from plain woven tape.

Butt blocks or fiberglass splices?

See our HowTo section for pictures of butt blocks and splices. For small boats we usually specify butt blocks. A butt block is very simple: a piece of plywood epoxy glued on top of the two pieces to join. Very often we use that extra thickness in a strategic place as a reinforcement. Often, we hide it between frames or under seat. Another method used on larger boats is a fiberglass splice, same principle but with fiberglass. It is important to use biaxial as we specify because of the fiber orientation. In all cases, the seams between plywood panels are also joined but the fiberglass seams of the boat. For larger boats, they are covered by several layers of glass in and out. The resulting joint is always much stronger than the plywood: try to break one of our butt blocks or splice and it is the plywood that will fail, not the joint. Visit our builder's web sites for pictures of the two methods.

How much fiberglass do I need to cover the bottom?

Probably none: except for the smaller boats (less than 14'), the bottoms are made of fiberglass!
Almost all our bottom panels are made of plywood with glass on each side, a fiberglass sandwich.
You may ask the question because most other designers announce the bottom fiberglass as an option but that is because they design plywood boats. Our are composite boats and the fiberglass is already there.
For the small boats
It is not necessary to fiberglass the bottom for strength or resistance to water: all parts are completely coated in epoxy. You may want to fiberglass for resistance to abrasion if you drag the boat on beaches or expect to run aground.
First check your plans: the fiberglass for the bottom may be on the plans. If not, it is very easy to estimate: look at the plans, nesting drawing. You will see the bottom panels on standard 4x8 plywood sheets. That is the area you need.
Another method is to take the length of a small boat with a safety margin. 50" wide fabric, 6 to 10 oz. woven is perfect and can be bought by the yard from our online store:

How to make putty? Glue?

Glue and putty recipes are in the Epoxy Book shipped with our kits. Glue and putty are made of epoxy resin mixed with fillers. For glue we use woodflour; for putty, a mix of microballoons and silica. Viscosity varies from ketchup style for glue to peanut butter for putty. It varies with the amount of fillers used. Also see our HowTo files.

What are the steps taken to finish the hull surface?

The experienced builder will reduce the need for fairing and sanding with clean fiberglass laminations and the use of plastic sheets or peel ply on the last layer. In a nutshell: 1. Fair hull shape 2. Prepare surface 3. Paint or varnish - Reduce the need for sanding with a sheet of plastic or peel ply on the last fiberglass layer - Use a resin slurry to fill imperfections if any - Switch as soon as possible to a high build primer. Those thick paint primers sometimes named sanding primers are easy to sand. Build a small boat first: it is easier to make mistakes and fair a canoe than a 22' boat.

Why do you recommend gaps between parts?

Since the strength of the joint between parts comes from the fiberglass seam, there is no reason to have a tight fit.
There are however very good reasons to have gap between panels and other parts of the boat:
- we want to avoid hard spots. A hard spot is a place where one part pushes hard against another. Loads will concentrate in those hard spots and that may result in failure. We want to spread the efforts on the hull and this done by distributing the loads over the full length of a seam through the fiberglass tape or fabric.
This is not a weird requirement for our plans but an important factor in composite boat building. It is mentioned in all text books about fiberglass boat building.
- another reason for avoiding hard spots is to avoid distortion in the panels and "kinky" curves in the panels instead of smooth/fair lines.

We recommend gaps of up to 3/8" between panels and between the hull skin and it's internal framing: bulkheads, stringers etc.

Materials and their use

Can I use polyester instead of epoxy?

No. If the plans specify epoxy, you should use that resin. Polyester does not bond properly to plywood and will delaminate.

What kind of resin should I use?

All our plans specify epoxy resin exclusively. Polyester or vinylester are not acceptable. Polyester does not bond properly to wood and is not sufficiently resistant to moisture. With polyester, water will find it?s way to the plywood and result in rot, not with epoxy. Use a quality marine epoxy like the one we sell in our kit: it does not cost more.

What is the shelf life of epoxy resin?

Epoxy has an almost unlimited shelf life. You can keep epoxy for years and it will be as good as the first day. In very cold weather, epoxy may crystallize. It will become liquid and clear after warming up and will have exactly the same properties.

What type of hardener speed?

We sell three different hardener speeds. See a table of cure speeds at BoatBuilderCentral. You can mix different hardeners for even more precise control.

Which type of fiberglass should I use?

Do not use fiberglass from an auto part store or fiberglass with mat. The fiberglass that we specify is much stronger and is easier to use even for a first time builder. It bends around corners with less air bubbles and requires less resin: in the end, it will cost less and be stronger. Fiberglass application techniques are discussed in our How To files but here are some important points: - Cut all your fiberglass pieces in advance, check them for size on the dry plywood. - Try to work wet on wet. That means applying fiberglass over putty that is still wet or soft and layers of glass wet on wet, on top of each other. You will work faster and eliminate the need for sanding between coats. Your lamination will have a higher glass content and be stronger. - Less resin makes a stronger lamination: squeeze the excess resin out with a plastic squeegee. - Cover the last layer with a plastic film like polyethylene, roll it down. The plastic will produces a smooth surface with almost no edges showing. Very little sanding will be required. The resin does not stick to the plastic. - For final fairing, switch as soon as possible to paint primer. It is easier to sand than cured epoxy resin.

Do I have to use marine plywood? How about cheap plywood?

It depends on the boat and is indicated on the plans or at the study plans page. Some general guidelines: . For a small boat that does not stay in the water, inexpensive Lauan or other exterior plywood is just fine. . For a utilitarian style boat like our OD16-18 or our garveys, good exterior with no voids is a good choice. . For offshore going sailboats, fast planing power boats and for all boats that will stay in the water for more than 2 weeks at a time, we specify marine plywood. This is required for structural reasons mostly. Those are the minimum specifications. Compared to the total cost of the boat, the difference in cost between quality marine plywood and cheap plywood is small: less than 10%. Marine plywood like Okume or Meranti are the best choices: they have superior mechanical characteristics, bend easily and are easy to work with. Build with marine plywood to save many hours of work and obtain a much better looking boat with a higher resale value. A good compromise if plywood cost is an issue is to use marine plywood for all hull panels and exterior for the framing and inside.

Is 1/4" (6mm) plywood not to thin?

For our small boats, 1/4" is used on the sides and sometimes the bottom and it is the proper thickness. Think of an inflatable boat: it is the water that supports your weight, not the fabric or in this case, the thin plywood. In our larger boats and power boats, there are other loads to consider but in those cases, the hull is NOT made of 1/4" (6mm) plywood. It uses 1/4" plywood as the core of a composite sandwich: the plywood is covered on each side with biaxial fiberglass and epoxy. The resulting panel is not only 3/8" (10mm) thick but it is stronger than 3/8" marine plywood, stronger and stiffer than a 3/8" standard production single fiberglass skin. Another advantage is that the thin plywood core is very easy to bend: you would not be able to build those hull shapes from stiff 3/8" (9mm) marine ply. Altogether: easier to build and stronger: a win-win material!

Can I use foam instead of plywood?

Foam sandwich is a good construction method for boats 25? and larger. For small boats, the use of foam would result in a heavier boat because of the skin thickness required for resistance to puncture.

What type of paint should I use?

In all cases, the epoxy resin must be painted or varnished to protect it from UV's. Almost any paint can be used on our epoxy resins. If your budget is limited, latex porch paint will work. You must sand or scrub then clean the cured epoxy before painting. A better finish is obtained with marine enamels and the best looking boats are painted with two part polyurethane paints. Those paints produce the highest gloss but some are difficult if not dangerous to use. We sell a safe, water reducible linear polyurethane that can be applied by spraying or with a brush. Gel coat is not paint: it is a polyester resin used in female molds. The gelcoat of high quality production fiberglass boats is often painted with linear polyurethane. It gives a much harder surface with a much higher gloss and better resistance to moisture. For the absolute best gloss, use a clear coat as final layer. Epoxy can also be varnished. A proper fiberglass lamination is transparent and our epoxies have a slight amber color. Use a good marine varnish like Z Spar.

Plans and dimensions

Can I build more than one boat from my plans?

No. You purchase a license to build one boat from the plans.
The designer still owns the copyrights to the plans and except for shop use, you can not reproduce the plans, resell them or give them away.
This is standard practice and allow us to keep the cost of stock plans low. A custom design cost several thousand $!
If you want to build the boat professionally, you must pay a license fee per boat.

What are all those nautical terms used in your plans?

We need to use the proper term for precision but it is easy. See this HowTo file for the most common terms.

Are electrical and engine installation diagrams included?

It depends on the boat.
For outboards boats, we sometimes show suggested electrical wiring for accessories on the plans or for the larger units, we include a separate electrical diagram to use as a starting point. See the plans description. The diagram shows connections to batteries, switches, panels and some basic instruments, a bilge pump etc.
Outboard engines are sold with an electrical harness and controls. To install an outboard is just a matter of plugin the harness and connect the control cables. We show chase tubes if applicable.
For inboard engines, at minimum, we show a standard engine with engine beds and sometimes exhaust and cooling.
For straight shaft inboard, we show shaft, prop, stuffing box, strut etc. with part numbers.
For all power boats and for large sailboats, we show fuel tanks and vents, fills, routing of hoses etc.

Can I modify the plans?

Yes. One of the major advantages of building your own boat is that you can customize your boat to fit your preferences.
To change seats or lockers size or location is easy but beware of hull and structure changes or scaling. They may have unexpected consequences.
Keep some important points in mind when making changes:
- the structure like bulkheads and stringers spacing must be respected
- you can not change the materials specifications: the boats are designed with a safety margin and are strong.
- if you add or move components, try to keep the center of gravity as designed and the weight within reasonable limits.

We will design some modifications or changes if we feel that other builders may be interested but if you modify one of your plans yourself, you are on your own for all the calculations.
If you consider major changes, it is often easier to start with another plan closer to your requirements. Ask for a new plan on our message board and we may respond that we have one in the works.

Are the dimensions for the sails and masts on the plans?

Yes: all plans for sail boats include complete sail and rigging drawings. The blueprints show at least one sail plan, in many cases two. Depending on the boat, we specify Aluminum or wooden spars. For many of our small boats, the spars are very easy to make from a couple of boards epoxy glued together, a very inexpensive solution. No hardware is required for those small boats. All sail boat plans include at least one sail plan with dimensions, fabric type etc. Your sailmaker or your can cut the sails from our plans.

How do I transfer lines from the patterns?

It's easy: we explain that with pictures in the plans description pages at
Click on "details" next to the plans order button.
Note that we supply not only patterns but also all the dimensions: you choose which method you prefer and you can also use one method to check the other.

Can I have the CAD files (DXF)?

No. If you have a CAD system and access to a plotter, you can plot your own patterns and details from dimensions taken from the plans. If you have access to a CNC router, you can extract router specific files from your files: see your CNC program instructions.

Can I enlarge or scale boat XYZ?

Yes, you can scale by 10% maximum but it is not going to be easy.
- The first problem is the dimensions of the panels.
If you have seen our plans, you know that we show the exact size of all developed panels. When you change one dimension, most of the panels change.
You can scale the panels. If you stretch the boat 10% lengthwise, scale all lengths 10%.
If you scale the whole boat in 3 dimensions, scale all dimensions.
- The second problem is one of scantlings and hydrostatics.
If you enlarge the boat more than 10%, you must recalculate the framing and the specifications of the panels: thickness, fiberglass layers etc.
A 20% increase in length means a 73% increase in volume and around 50% in weight. Your boat may float too high or too low.
- The third problem is the most important one: plywood usage.
We work hard on optimizing the use of plywood, reducing waste and locating the splices strategically. If you increase a dimension by only one inch, a panel that was designed to fit on three sheets of plywood will suddenly not fit anymore. You will need four sheets and the splice is going to be in a weird place.
This has a chain reaction effect and we have seen cases where a small enlargement of the hull resulted in a plywood increase of 75%!

Is this particular to our plans? Are other plans not easier to scale?
Not at all. Most plans from other designers do not give you the dimensions for the developed panels and do not show the nesting on the plywood. There isn't much to change in those plans because the information is not available. If you want, you can use our plans like those less detailed ones but construction will be more difficult, just as with the other plans.

You may choose a design because it is easy to build or economical but wish that it was just a foot longer.
Add a foot and the boats is not easy and economical to build anymore.
Bottom-line, avoid scaling our plans. If the boat looks too small, choose another design.


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