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BOAT BUILDING METHODS
FOR THE HOME BOAT BUILDER

(Last up-dated 28/08/09)

There are many methods of construction available to the home boat builder - on this page l will discuss the most popular methods used and compare them so that the new builder can make a good choice for his/her boat building project.

The method used will depend on the materials chosen or available, the skills and the tools available.

Here is a very brief look at the materials often used :-

MATERIALS USED IN BOAT CONSTRUCTION

Material

Notes/Comments

Wood Easily available in various different qualities (ie. Exterior vs Marine plywood).
May be used by those with both low and high skills.
Can be worked with fairly basic tools as well as with very sophisticated tools.
Can be used in less than perfect building conditions.
Has the qualities of strength and stiffness and can be joined together using both simple and more sophisticated methods and glues etc.
Ease of repair depends on method of construction.
GRP (glass reinforced plastic) Single skin - materials are easily available but require controlled conditions for curing etc.
Fairly unpleasant to work with.
Requires a lot of tooling (ie. the construction of a 'female' plug from which a 'male' mould tool is taken - therefore not suitable for "one-offs" and is usually used for mass or batch production.
Not too difficult to repair.

There is a method using sheets of pre laminated grp which can be stitched together much like a stitch and tape plywood hull and then laminated over on the inside (the White Swan can be built this way as an alternative to ply construction - in fact most stitch and tape designs can be built this way - this is still a very messy process.

Foam reinforced grp (foam sandwich) - uses a much rougher/cheaper building jig (no need for expensive mould tools) but still a lot of grinding etc to do and care has to be taken to make sure that the bond between the inner foam core and grp outer skins is good.
Not so easy to attach fittings too (the foam needs to be replaced with plywood where fittings are attached which means a lot of pre planning is required.
More difficult to repair than single skin.
Steel Low cost.
Construction materials easily available and building skills easily acquired.
Easy to repair.
Can suffer from condensation and corrosion may be a problem.
Usually heavy construction and therefore often unsuitable for craft below 20' (6.1m).
Aluminium Relatively high cost of materials.
Requires specialist welding skills.
Has a cold feel (aluminium seats etc feel cold to the touch).
More or less corrosion free and light weight.
Relatively easily repaired with the correct welding equipment.
Ferro-cement Layers of chicken wire over a steel rod framework and impregnated with cement.
Basic skills required.
Difficult to attach other materials to (ie. wood bulkheads, decks etc).
Heavy construction for boats over 25-30' (7.6-9.2m).
Can suffer from internal corrosion.

Several of our designs (for plywood) have been built in steel and more often, in aluminium (canoes and dinghies especially). For steel, we have had to remodel the hull to give more displacement volume by increasing beam and hull depth (see our 22' Black Swan yacht) and we can do this for many of our designs.

Some of our wood designs have also been built in GRP and in foam sandwich and we can draw up the details to do this - however, the majority of the designs we offer and most of our new design work is for construction in wood, so let us have a brief look at the different ways in which wood can be used for home boat construction.

 

MOST COMMON METHODS OF WOOD CONSTRUCTION

Method

Brief Description

Advantages/Disadvantages
Conventional/Traditional Construction Carvel Individual tapered planks edge to edge and fastened to a framework. Requires high skills, expensive materials, traditional caulking between planks or glued splines and heavy framework.
Lapstrake/Clinker Individual tapered planks with over lapping edges fastened to transverse timbers. Requires high skills, expensive materials. Requires regular maintenance and is difficult to repair. Can suffer from leaks as the hull gets older.
Cold Moulded Several layers of thin veneers of wood glued to each other over a jig or framework. Fairly high skills and maybe the production of a jig that becomes redundant. Also uses expensive materials - produces a very strong monocoque hull shell. Difficult to repair.
Modern Construction Stitch & Tape (Stitch & Glue/Tack & Tape) Pre-shaped panels of plywood stitched edge to edge giving a multi-chine shape with ply frames added. Can use low cost materials, requires low skills and only basic tools. The quickest, cheapest and easiest form of construction. requires the use of epoxy joins which can be messy.
Good for lightweight hulls.
Ply over Frame Plywood glued/fastened over a rigid framework. Moderate skills required - does not need extensive tools - takes longer than stitch and tape due to the conventional framework. More expensive in smaller boats than stitch and tape but perhaps less so in larger plywood boats.
Heavy weight construction.
Strip Plank Parallel strips of wood glued edge to edge over a temporary building jig and covered in glass/epoxy or wood veneer. Western Red Cedar is usually used (though not always) which is expensive - moderate skills required but more expensive/time consuming due to the building jig required. Fairly easy to repair.
Fairly lightweight.
Cold Moulded Similar to conventional cold moulded but sometimes vacuum bagged. Similar to trad' cold moulding but often used in conjunction with strip planking to produce a very tough hull.
Lightweight construction.
Clinker Ply Similar to trad' lapstrake/clinker but with joins between planks glued with epoxy rather than copper clench nailed. Requires expensive materials (ie high quality multi laminate plywood), high skills and extensive tools (ie. rebate planes etc). Not easy to repair.
Lightweight construction.
Note - there are many more methods of wood boat construction - Ashcroft, French Carvel etc - but they are not popular amongst home builders often due to their complexity - for information on these methods read books like Boatbuilding by Howard I. Chapelle etc.

 

 

OVERALL COMMENTS AND RECOMMENDATIONS

All the comments and descriptions above are very brief but the following basic conclusions can be drawn from them :-

1.  For first time builders with few wood working skills and a shallow purse, stitch and tape is the construction method to choose - also if the amount of time you can put to the build is low, then again, this is the method to go for.

2.  If you want a lightweight car-toppable boat, again, stitch and tape is the method to choose although if you have good wood working skills or are willing to learn and do not mind spending the extra on good quality materials, modern clinker ply and strip planked Cedar also produce light hulls.

3.  If you are only looking at plywood for the main construction material then for boats over 20' (6.1m) in length, l tend to use ply over frame construction - this method gives you a rigid framework and point of reference to work too - joins in the hull skin panels usually have a wood stringer behind them rather than tape and epoxy. I have used stitch and tape for some quite large craft but fighting with plywood panels longer than 20' of 3/8" or 1/2" (9mm or 12mm) thickness and trying to get them stitched together in the correct place without a reference framework can be very frustrating unless you have lots of hands to hold the panels in place. The amount of epoxy used in stitch and tape boats over 20' (6.1m) also tends to be large and never seems to want to stay where l put it!
Modern frameworks tend to be of egg-box plywood construction rather than the old fashioned solid wood affairs with few, if any redundant members - a well designed ply over frame hull will have ply bulkheads and girders slotted together with these components forming bunk and locker fronts and partitions.

4.  A modern strip planked hull which is veneered or coated in glass/epoxy on the outside is, effectively, a single monocoque shell which does not leak and which requires less framing and will last - it also gives the appearance of a conventional round bilge carvel planks hull without all the disadvantages - building skills required are not too high so, if you have the time and the additional funds, this is an excellent construction method.

5.  Clinker ply is also a very effective way of producing a beautiful monocoque shell - it takes more skill, better and more extensive tools and more funds - but it has been used by plenty of first time builders who have been prepared to gain the skills and use the good reference manuals available for this method,

6.  Also consider resale values - a nicely built strip planked or clinker/ply hull will retain there values and become an investment. Stitch and tape hulls also retain a good value but will not have the same resale value.

7.  If you are considering building a bigger boat which, no matter which construction method you use, will require a bigger investment in time, money etc and you have not built before, consider building a smaller boat (ie. a dinghy to be used as a tender for the bigger boat) which uses the same method of construction, first.

 

THE LINKS BELOW WILL TAKE YOU TO SEPARATE PAGES DESCRIBING EACH OF THE 4 MAIN WOOD CONSTRUCTION METHODS USED BY HOME WOOD BOAT BUILDERS

Stitch and Tape Ply on Frame Strip Planking Clinker Ply