Powerboating - Part One

Over the past decade or so, the idea of cruising the ocean to romantic places has undergone many changes. And probably the most important of these has been the type of boat people are using.

The predominant craft of times past has been the yacht, with visions of sun-soaked blue seas under spreading canvas conveying the image that has led many to embrace this dream. But for those who want escape from the tethers of ropes and cloth, yet still yearn for the adventure of the sea, there is the powerboat.

These articles are not an attempt to enter that hoary old debate - power versus sail. Rather it is devoted to people with a passion for powerboats - people who would like to live on one for awhile and even do some cruising.

To members of the boating fraternity whose absolute joy is thrashing about oceans heaving on strings, I say great, but it's not for me.

If you love boats that travel long distances at angles approaching the horizontal, then read no further. However, if you appreciate that wonderful discovery called glass, and like it between you and the weather, if your idea of travelling from A to B is a straight line, and if you simply just like boating, then you may enjoy reading these articles.

Hopefully there will be parts that will help you get even more enjoyment from your boat than at present. If you are at the stage of purchasing a vessel, your first or umpteenth, then we hope the following pages will assist that venture.

While writing this series, I wanted to keep a budget firmly in mind. I have a fiscal plan and I think most people are also budget conscious. Obviously there are alternatives (to what I have suggested) that would be far superior - albeit at far greater expense. If money is no object you will easily achieve that 'perfect boat'. But if the craft and its systems are a compromise between the desirable and the affordable, then a few of the ideas contained herein may make life aboard a fraction easier, boating a little more pleasant and life more hassle free. Also, because this is not intended to be an encyclopedia of boating, I have limited all discussion to craft generally in the 30-50ft range with inboard motors, as these are the most popular in the context of my articles.

My credentials are humble and have been attained largely by experience rather than formal study. I am deeply indebted to the many people whose brains I picked when mine faltered. Many companies have been generous with their time and resources and I have endeavoured to mention them where possible. To those who were reluctantly omitted, I can only apologise.

I recognise that there are many ways of doing things and firmly believe in the axiom "there's always a better way". If, like me, you love messing about in boats and can see a better solution to some of the things that will be written about during this series, perhaps one day we'll meet, have a couple of cold beers and talk about the sea. I know I'd like that.

So let us begin at the beginning, and imagine that we are looking for the boat of our dreams. It sure would help if we had an idea of the different types and styles that are available, so that's where we'll start.

OVERVIEW
When examining the hull of a typical powerboat, the two most obvious aspects are its form or shape, and the material used in its construction. Hull forms generally fall into one of three broad categories - planing, displacement, and semi-planing.

The materials used in their construction are much wider, from the now seldom seen ferro-cement to the extremely popular fibreglass. Later we will examine these subjects in some detail.

WHAT'S THAT PART CALLED?
Various parts of a boat's hull have specific names, with some harking back to antiquity. The illustration on page 230 (overleaf) shows some of the more common terms.

Don't be dismayed if you don't know a futtock from a gimbal, as most of us pick up the terminology as time goes by.

HULL DESIGN
The shape of a hull is determined by the designer or naval architect when the vessel is on the drawing board. The boat's purpose will often determine it to be a displacement vessel or planing craft.

When a boat sits in the water it makes a hole in it, and if it were possible to lift the boat up out of the water and not have the water flow back into this hole, there would be a perfect impression of the hull on the surface. If this imaginary hole was filled with water, the weight of that water would exactly equal the weight of the boat. This weight is called the boat's displacement.

If the designer had a bad day and the boat displaced less weight of water than its own weight, then it would sink. This is the fundamental law of hydrostatics.

Assuming that our architect knows his job, we could put our boat back in the water and admire it floating at the dock while we observe a few finer details of his skill. Because boats are primarily designed to go in a forward direction, the hull has been shaped at its forward end to assist in pushing the water aside as it travels through it. This part of the vessel is called the bow.

The bow can be a variety of shapes - from very fine (like an axe head) to very bluff (similar to the front of a bathtub). It can be deep (running straight down to the bottom or keel of the craft), or shallow (not joining the keel until some distance to the back of the boat). Each shape will be part of the designer's attempt to produce the best possible form to suit the vessel's purpose.

I could go on at some length over many aspects of design, but enough has been observed at this point to understand the difference between a planing hull and a displacement hull.

DISPLACEMENT HULLS
As a displacement hull powercruiser gains speed, a wave starts to build up at the bow, and this wave gets bigger as the boat moves faster. At the same time, the stern or back of the boat sinks further and further into the ocean. If the vessel had unlimited power and could keep pushing forward at an ever-increasing speed, a point would be reached where the stern could literally go under, and the boat would sink.

In fact, some of the fast clipper sailing ships of the 19th century are believed to have disappeared in this fashion. Sailing before a strong wind with all sails set, a sudden squall would drive the ship to such a speed that it would literally 'sail itself under' before the crew could shorten sail.

Obviously then, there is an upper limit to the speed in which a displacement hull can travel through the water. This is called the Theoretical Hull Speed and has been dealt with previously in these pages.

It is expressed mathematically as 1.4 times the square root of the waterline length. Thus, a displacement hull with a waterline length of 30ft would have a theoretical speed of 7.6kt.

Now, we have all seen boats with smaller waterline lengths go a lot faster than this - a small dinghy with an outboard is a classic example. So how is this made possible? The answer lies in the art of the naval architect and brings us to the second type of hull form, the planing hull.

THE PLANING HULL
If we looked at the underwater shape of a planing hull, the difference between it and a displacement hull is immediately apparent. The underwater shape is composed of more flat sections, the bow is fuller and the keel a lot less defined.

The purpose of all these changes is to produce a shape that will have little difficulty in climbing the wave at the bow and, if enough power is applied, break over the wave and virtually sit on top of it. When this happens, the hull is no longer displacing its weight of water; it no longer has to push this enormous mass out of the way in order to go forward; rather, it uses its power to skate across the top of the ocean.

Because of this, the planing hull has no theoretical upper speed limit and is restrained only by the available power of its engine.

THE SEMI-DISPLACEMENT HULL
These two schools of design can be merged to produce a hull that attempts to combine the best features of both. Hence there's the deep forefoot and accentuated keel found on displacement hulls, but with the flat planing surfaces and shallow deadrise aft which are more common on planing craft.

This results in a boat that will run to its hull speed easily with moderate effort, and will not produce the enormous bow wave if further power is applied. Instead, it will gain a further knot or two without looking ungainly. This type of craft can be made to get up on the plane with the application of enough grunt, but they are seldom a pretty sight (ie. pretty much like an overweight person running a marathon).

COMPARISONS
To compare the advantages and disadvantages between these basic hull forms is generally fruitless, as boats are normally purchased to suit particular applications. However, some fundamental observations can be made.

Firstly, if you want to go fast, then a planing hull is the only way to go. The trade off, of course, is that a larger percentage of the overall displacement of the boat will be given over to the propulsion system (engines, fueltanks, etc), and less to the other aspects of ship design. Speed costs money, both in capital outlay for the engines, etc, and the cost in running them.

However, a displacement-type craft with a speed of, say, eight knots would not suit a lot of people, and as a consequence these tend to be in the minority when looking at the output of modern pleasure powerboat production lines.

The semi-displacement hull with a length of between 30-50ft and a hull speed of around 12kt has proved popular over the years, and many examples of these easily driven craft are still seen on the water.

In the end it comes down to individual choice. People with a passion for fishing seem attracted to planing hulls to enable them to get offshore quickly and to run for home when bad weather threatens. Those who intend to cruise fairly long distances and perhaps live aboard, lean more to the displacement and semi-displacement style, since both of these tend to provide more useable room than the alternatives.

SIZE
After deciding on the style of boat that will best suit your needs, the next most important question is how big? Obviously, size and comfort go hand in hand. The larger the craft, the easier it is to stay aboard for extended periods. But the bigger the boat, the more difficult it is to handle without experienced crew, especially in tight marina situations. And, of course, big boats generally cost more money to purchase and maintain.

Also, size and length are not directly correlated - one popular semi-displacement on the market today has an overall length of 32ft and a displacement of seven tonnes. The next model from the same manufacturer is 36ft and displaces 11 tonnes - a much larger craft than the addition of four feet would suggest.

It goes without saying that the larger boat would require much more horsepower to propel it through the water.

A very rough rule of thumb for displacement and semi-displacement hulls is 20hp/t of displacement as an average. Based on my own observations, it would seem that 30ft is about the minimum overall length of boat that two people can stay on for any reasonable period and still have a lifestyle that does not resemble camping.

CONSTRUCTION
How and what a boat is made out of is extremely important in the context of how much it will cost and, ultimately, what it will bring when the time comes to sell. This does not mean that one form of construction is better than another, rather it is more what the market demands.

When buying a boat, it is always better to purchase a recognised design than a custom-built 'one off', simply because it is easier to establish the boat's value on the open market.

For instance a 1980 model XYZ 38ft aft-cabin cruiser with twin 120hp engines might have an upper value of $145,000 and a lower one of $120,000. However, a similar boat constructed as a once only project, even though professionally built and in extremely good condition, will be much more difficult to sell as it can only be advertised by description and not by reputation.

The following is a reasonable guide to the more usual types of construction:

Fibreglass
By far the most common and popular material used in the manufacture of modern power craft, fibreglass came to the fore during the 1960s. Its immense strength, ease of manufacture and maintenance and the ability to mould it into complex shapes has led it to become the number one choice around the world.

This is not to say that it is without problems, as any owner faced with a major blistering (osmosis) repair bill would readily attest. However, I feel that fibreglass gives less worry over the years than any other material.

A word of warning at this point. Some vessels that are advertised as 'fibreglass' are in fact only made of that material as far as the hull is concerned. The decks and superstructure are built of plywood with a thin layer of glass mat and resin over the top. This is then filled and spray-painted.

The end result looks to all intents and purposes the same as a full fibreglass construction, but over the years, rot can attack the plywood, and by the time this insidious disease is apparent, repair costs of thousands of dollars have accumulated.

This style of manufacture was not entered into with any thought of deception; simply it was a method that allowed the manufacturer more freedom in customising the final article as he was not locked into moulded parts. Much of this construction method took place in the Far East, notably Taiwan.

Some of these boats are approaching 40 years old and are in fine condition, as a lot depends on the maintenance done over the years. Sadly, some are only fit for the scrap heap due to extensive rot.

I was once involved in a quotation to cut a small amount of rot from the flybridge of a popular 56ft cruise boat. The owner had a figure of less than $2000 in mind when the shipwright commenced looking at the problem. Four hours later, an estimate of $100,000 left the owner ashen-faced. At the time I thought he was going to have a heart attack!

Be very careful when buying and always engage expert advice.

Timber
Everyone's favourite, timber has been the stuff of boats since time immemorial. I don't think anything delights the eye more than a well-constructed wooden boat of classical lines.

Cost is always the big factor when considering timber, as that classic will command a top price if it's in good condition, and if it isn't then it will take top dollar to bring it up to the mark.

There are many forms of timber construction - carvel, clinker, diagonal plank, to name a few. Also there is plywood, and while I do not wish to seem prejudiced against this material, it is especially susceptible to rot.

Again, always take professional advice before purchasing.

Steel
More common in the commercial side of boating than in the pleasure area, steel boats are immensely strong and durable.

For those people who are intensely boat proud, I would hesitate to recommend this medium, as chasing rust is a fulltime task. It is not hard to get a steel craft to look 100% while it is sitting in a marina, but two or three days of punching into a seaway will find every miniscule pinhole in the paint system, resulting in bleeding from that point, with the result that it soon looks like it hasn't seen land (or a paintbrush) for years.

These are only minor problems and are soon fixed, but the boat sure looks like a rust bucket until this is done. I should know, I used to own a steel boat.

Steel boats tend to be cheaper to buy but harder to sell than glass or timber versions.

Aluminium
Not often encountered in smaller cruising power craft, this tends to be the preferred medium for the megayacht of the 100ft-plus mark. It is an expensive material to build with and is mostly limited to the one-off custom manufacturers. It is easy to maintain and suffers from few problems, although electrolysis can attack it.

Aluminium boats can be difficult to sell due to the 'one-off' syndrome, although they are generally well accepted by the boating public.

Ferro-cement
It is probably possible to build fibreglass footpaths, but why would anyone bother when there is already a perfect medium called concrete. And vice versa.

I rest my case.

LAYOUT
This subject is more important then the overall size of the vessel, since a well-designed and laid out smaller boat will be easier to stay on than a poorly planned larger one. The following list includes some of the things I consider essential, or at the very least desirable, when considering a cruising powerboat.

Enclosed toilet
I hardly need to point out the advantages of this feature in any boat. I could not imagine being onboard for any sort of time without a private toilet.

Ideally the toilet itself would be electric, with treatment facilities and holding tanks.

The genius of the human being for complicating the simple is exemplified in the marine toilet, with some antiquated horrors requiring a plethora of different valves and levers to be adjusted in sequence while pumping for one's life. Thankfully these are becoming a memory, and an electric toilet, or one of the vacuum types make life a lot easier.

Shower
These are generally combined with the enclosed toilet and are not too difficult to incorporate into a boat that does not already have one.

The cabin should have ample clothes storage space, preferably a hanging locker of some sort.

There needs to be storage for spare linen and towels as well as shoes, bags and all the usual sort of paraphenalia for the business of living.

Cooking facilities
Food becomes more important when staying aboard, simply because most of us have a great deal more time to devote to its preparation. A two-burner cook top, gas or electric, should be the minimum requirement. An oven is almost an essential, but I can live without a griller (the barbecue substitutes).

A generous amount of benchtop space, good food storage cupboards and sufficient storage for cooking and eating utensils is also advisable. These items are easily the most neglected by the modern boat manufacturer.

Outside area
This is often overlooked when considering which particular boat suits your needs. There are some craft which have been developed with accommodation solely in mind. The saloon extends to the full beam of the vessel and as a consequence there are little or no sidedecks to walk around, making a trip to the foredeck something of a balancing act; in fact the whole business of moving around the outside of the boat is difficult.

This sort of design is more often seen in the smaller powerboat, but I have seen 50-footers with the same problem. How the crew ever gets to the front of the boat in a hurry is anyone's guess. This leads us to the next point of boat design.

STYLE
Basically, powercruisers have developed two distinct styles: sedan and aft cabin. The aft cabin configuration is very popular, as it generally allows for two separate cabins at each end of the boat, with both generally having their own separate toilet facilities.

The cabin in the aft section of the vessel often extends to the full beam, allowing a walkaround double berth with ensuite shower, toilet and in some instances a bath! True luxury.

The forward cabin is more often a V-berth with a much smaller toilet and shower set-up. This arrangement is ideal for people with children or those who regularly entertain guests.

A sedan-style boat has its cabin or cabins forward, a large main saloon and an aft deck (more commonly called a cockpit).

If two boats of the same overall length but each of different style were placed side by side for comparison, the dissimilarities would be readily apparent.

The sedan would generally have a larger main saloon and more accessible outside area, by virtue of its cockpit. If it had two cabins up forward, each might have its own facilities, although it would be more common for these to be shared. The cabins would naturally be very close and not terribly well soundproofed. This could lead to problems.

Aft cabins can suffer from an accessibility problem, for some of the engineering and the engineroom can be a servicing nightmare.

The sedan mostly has a large storage area (lazarette) under the cockpit, and additional water and fuel tankage can be placed here as well. Also, the cockpit area can be enclosed with canvas or clear plastic to increase the living space.

The deck over the aft cabin on an aft cab is not as an attractive place to gather as the cockpit of a sedan, and the sedan style generally looks prettier, although this is not always the case.

In the end, you pays your money and you makes your choice. It is entirely up to you.

Flybridge
This feature is found on most modern powerboats, simply because it is popular and practical. The elevation assists in navigating the boat in tricky circumstances and it is a thoroughly enjoyable place to be.

It is becoming more common for manufacturers to offer the elimination of the lower steering station as an option. This has the advantages of cost-saving and also being able to use the lower helm area for other uses, such as an extended galley or dining arrangement. The downside is that when the weather is foul there is no comfortable lower helm to steer from, although many people have overcome this problem by the addition of 'clears' (ie. clear plastic covers that completely enclose the flybridge).

SYSTEMS
Most of the systems on a boat revolve around our comfort and wellbeing. If they are poorly planned or suffer from bugs, then boating will not be the pleasure it can be.

When considering a boat, pay particular attention to the following systems, and think how you would cope without them.

Water
I don't think the boat has yet been built that can carry enough water. As a guide, 200lt per person per week would be about the minimum for comfortable cruising, assuming that there is a shower onboard.

Watermakers and such like aside, there are a few tricks that can be used to extend this; one is saltwater piped to the galley sink. This water can be used for dishwashing and general sink cleaning and it is amazing the difference it can make.

Although a pressure water pump is not an essential, it sure makes a difference to those hand or foot pumps of days past, although it does tend to increase water usage.

While on the subject, a water heater is nice, preferably one that operates off both the engine and electricity.

Electrical
Generally electrics are the biggest headache on any cruising craft, with entire books solely devoted to this subject.

It doesn't have to be a nightmare though and a lot depends on the age of the boat and how well wired the boat was in the first place.

I have observed that over time and a succession of owners the wiring of most boats devolves to a rat's nest of incomprehensibility, particularly on the DC side. Happily, most of this can be corrected and we will delve deeper into electrical systems in a later instalment.

On the 240V AC side, an auxiliary generator backed up with a high output inverter is pure luxury, or at least it used to be. I now find both of these items on my essentials list.

Refrigeration
Possibly second only to the enclosed loo in importance, with some people putting it at the top of the list. Good refrigeration is a must for people contemplating staying aboard for extended periods.

Autopilot
Sure makes life easier for those long passages; in fact I use mine almost 100% of the time, so this is on my 'must-have' list.

Airconditioning
Rapidly becoming the most requested option on the new-boat manufacturer's list. It's a bit like airconditioning in a car; difficult to do without once you've had it.

Dinghy
Generally, this is not considered a system but is one of the most intractable problems to solve. A dinghy that is of ample size to safely travel from the boat to the shore is often too big and heavy to stow easily.

TO COME...
For those who have not yet bought a boat, I hope this article has shed some light on your final decision. For the rest of us who already own one and would like to know more, we'll move on in future articles.

Just one final word - it is seldom we can get a boat that exactly suits all our needs. But just something is done a certain way, it does not mean that it cannot be changed to better fit your needs. Part of the fun of owning a boat is being able to change it to suit yourself...