The need for a risk assessment system

The following text is contained within the MCA document “Information on the Regulations Applicable to Pleasure Vessels”.

SOLAS V For Pleasure Craft

On 1 July 2002, some new regulations came into force, which directly affect pleasure craft users. These regulations are part of Chapter V of the International Convention for the Safety of Life at Sea, otherwise known as SOLAS V. Most of the SOLAS convention only applies to large commercial ships, but parts of Chapter V apply to small, privately owned pleasure craft. The following requirements apply to all craft, irrespective of size. If you are involved in a boating accident and it is subsequently shown that you have not applied the basic principles outlined in this document, you could be prosecuted. 


Regulation V/34 ‘Safe Navigation and avoidance of dangerous situations’, is a new regulation. It concerns prior-planning for your boating trip, more commonly known as voyage or passage planning. Voyage planning is basically common sense. As a pleasure boat user, you should particularly take into account the following points when planning a boating trip: 

The principles described make excellent sense, and are written clearly and pragmatically, yet that should not be taken to mean that they can be ignored: note the phrase “you could be prosecuted” in paragraph 1. The J Score Risk Assessment System is designed specifically to allow the skipper of a pleasure craft to apply these mandatory principles in a systematic way which can also be used as documentary proof of prior planning. It is recommended that the score is entered into the log book for each passage. 

The score can also be updated if circumstances change, and it can be worked out for several options, for instance to help choose between turning back, carrying on or diverting to a near-by harbour. 

Of course, merely working out a risk score is not actually a passage plan, and so not a substitute for one, but is a useful extra discipline. In the end, whatever the ‘J score’, the decision of what is acceptable or best rests with the skipper; a negative score does not automatically mean that the passage is dangerous, nor a positive score that it is necessarily safe. What I have found most useful is to analyse a plan with a series of ‘what if?’ scenarios; my wife gets sea sick and can no longer stand her watch for instance, or the weather deteriorates to force 7 etc. 

Using the ‘J’ Score Risk Assessment System 

For each passage (or even section of package) you work out the J Score. This takes into account four elements:

  1. Boat 
  2. Conditions 
  3. Crew 
  4. Passage 

Each is scored in a range between -5 and +5; positive is good, negative bad, and the total added up. The more positive the score the lower the obvious risk. 

The numbers in the scoring system are essentially logarithmic, so a +1 is an increase of risk by a factor of around 2.7. In this way 2 to 3 is the same factor of increase as 3 to 4 etc. This means that adding the final scores is appropriate as it's a multiplication of probabilities.


So how sea worthy is the boat? 

Let’s start by assessing what would merit a +5: 


Take off 2 points for any single point of failure such as a motor boat with only one engine or a sailing boat without engine. 

Table for Boat
Ocean passage maker +4
Offshore yacht +2
Coastal cruiser 0
Dinghy -2
Inland Cruiser -2 to -4

In reaching the above assessment factors such as length and weight, design features such as a lack of skeg, stability curves or length/displacement ratios should all be taken into account. 

Weather conditions 

I suggest that one uses a simple table based on Beaufort wind force in the open sea. 

+5 is perfect day (flat calm if a motor boar, F3 reach if under sail. Good visibility). 

-5 corresponds to F9 on the nose. 

Beaufort Force Down wind Up wind
0 +3 +3
1 +4 +4
2 +5 +4
3 +5 +3
4 +4 +2
5 +3 +1
6 +3 0
7 +1 -1
8 -1 -3
9 -3 -5

 Modify as follows for poor visibility: 

Limit the total to the range -5 to +5 Then look back at the boat score and adjust if need-be: the idea of this pairing of boat and conditions is that the worst conditions the boat is happy in without damage will have a score equal to and opposite that of the boat itself, ie their scores add up to zero. As an example an offshore cruiser of around 30 feet scores +2, and in the table for conditions -2 corresponds to force 7-8 upwind in open sea, and a bit more off the wind, which feels about right. 


This is done independently for each person on board. It is based on experience and fitness, and should consider attitude and general usefulness in a tight spot. Take off points for propensity to sea sickness. Children are not necessarily negative: being light and agile they tend not to hurt themselves, can rather easily be put to bed, are used to being told what to do or having to amuse themselves, don’t have much luggage and are quite happy not to have home comforts, showers or clean clothes. 

A suggested starting point is: 

YM Ocean or extended passage experience in the boat +4
YM Offshore, typical score for an owner/skipper in UK +3
Day Skipper, some night time crewing experience +2
Competent Crew level or equivalent +1
Admits to having ‘done some sailing’ 0
Complete novice, but a capable sort of person -1
A passenger or child of 10 or younger -2

Limit the score for each person to lie within the range +5 to -5. 

Total for the Crew 

To add up the total crew score divide into two groups; those with positive scores and those with negative.


Add up 


Add up all the negative scores and divide by the number of crew (including skipper) with positive scores. 

Total the lot and round to the nearest whole number (note that with a strong crew the total crew score can add up to a maximum of +10). A couple of examples show this more clearly. 

Example 1: Family holiday of a couple with three children of various ages. 

Example 2: ‘Boys’ delivery trip with three experienced adults. 


The passage is paired with the crew, so one way to consider this is to ask the question ‘what sort of person could do this as skipper?’ The passage and the skipper’s scores would then add up to zero. 

Estuary with little tidal difficulty: +2
Normal coastal cruise, eg Falmouth to Fowey  +1
As above, but in darkness  0
Coastal cruise with navigational issue, eg tidal gate or TSS  -1
Over night coastal passage or cross channel -2
Longer offshore passage, eg Biscay or length of Irish Sea  -3
Ocean passage -4
Southern capes -5