Compiling a Spares Inventory List for a Cruising Catamaran

Are we adequately prepared for our sailing adventures? Do we have all the gear and spares that we might need while cruising? These are complex questions to which there is no correct answer. How many times have we disposed of an item only to find that a week or so later we needed that exact item. This is the dilemma we all face when taking to the sailing/cruising lifestyle. Remember, weight is a big no-no for catamarans, so how much is enough and how much is too much?

We asked the Catamaran Guru team to give us a few suggestions of the spares that they carry onboard their own catamarans. We combined their lists and we tried to make some suggestions here for items to be considered. Please keep your personal requirements in mind whilst compiling your own spares package. There is ONLY one correct solution to this issue which is:- I had the part I needed when I needed it! Not having the spare part to get a system back to the manufacturers’ specification, does not mean the end of your cruising days but it certainly will make life a lot more pleasant.

Stephen Engine repair
Martin on Old Peculiar (Lagoon 450 F) says: “An important caveat to the spares inventory list is to make sure that you know how your boat operates and how the systems work so that, at a minimum you can troubleshoot a problem. A working knowledge of the many systems that go to make up a cruising boat will help flatten those bumps that you will encounter. A big consideration is to fully understand the foundation that you are working with. Age of the rigging, hours on the engines, condition of watermaker membranes, condition of the electrical system, pumps and navigational electronics etc”.

One last thought is to identify what systems are deemed critical to safety and determine if a backup system can be installed in parallel. Terry on Khaleesi (Lagoon 450S) says: “While crossing the Pacific in 2015, we had our primary Autopilot computer fail. We had a spare linear drive on board and this backup Auto Pilot helped us finish off a 4-day passage as hand steering was not a task we relished! But we immediately ordered a replacement computer and did the proper repair”.

Stephen suggests that there are some fundamental questions to be asked when working on a spares inventory list. As a starting point, consideration should be given to some of these items:

  • What are my cruising expectations, destination and time away from adequate spare parts?
  • How competent am I in the installation of a spare part? Some basic knowledge of your boat systems is highly recommended! Take classes to help you understand what you will be dealing with i.e. diesel engine classes or read this article about how a marine diesel engine works.
  • If I cannot install it myself, will I be in an area where help is available? If you plan to be in remote areas, be prepared to do most repairs yourself
  • What happens if I am underway and a critical item fails like an autopilot? Do you have a spare and can you fit it?
  • How can I manage with system failures using alternative means? Should I become familiar with some critical failure scenarios just in case? What alternatives are available? Can I do a “McGyver” repair if need be
  • Storage space? Even on a catamaran with oodles of space comparatively, you cannot carry the whole of West Marine with you!
  • What tools do I need?
  • Identifying critical systems versus convenient systems is a pre-cursor to building your spares inventory.

Let us explore the above questions in a little more depth.

  1. Assuming we are in a sailing catamaran, we most likely have three sources of propulsion. We have two main engines and we have sails. Except for the extreme case, a failure of one of these systems would only be an inconvenience.
  2. Failure of a marine head is not a big deal as it could be substituted by another head on the vessel.
  3. A domestic water pump could be replaced by a deck wash pump or one feeding a head.

So none of the scenarios above are critical repairs and the vessel can limp along. While inconvenient, the vessel will not be incapacitated. Therefore, our first point of call is to consider alternatives for critical systems on our own vessel. Now suppose you go to an out-island and take on some contaminated fuel! This most likely is going to affect several systems. We may now have no engines, no generator, no propulsion or electrical charging capability. In this instance it would be good to have a means of repair on hand.

General Ship Spares List

The following is a list of considerations for a spares list based on our personal experience. We have some spares that have never been used, some that are convenient to have and some that we consider a must have. They are broken into sections commensurate with likely use.

Essential Spares• BEER or RUM! This can be traded for spares and assistance worldwide. Also helps celebrate a successful repair.

• Emergency through-hull plugs
• Snorkel/Mask/Fins
• Locktite underwater epoxy, 2 part in a tube.
• Multi-meter and knowledge of how to use it!
• Fuses for all system fuses
• Selection of hose clamps
Self-sealing repair tape
• 3M 5200 / 4200
• Spare length of line, preferably to match the longest line onboard, we have several of all lenths, strenghts and thicknesses.
• Replace your current Topping lift with a Halyard size line so that if the main halyard fails ,you have a spare halyard.
• 100 feet of Amsteel, can be used to temporarily repair standing rigging
Tool kit, combination toolkit (e.g. Sears)
• Boat maintenance manual, either electronic or paper (Chapman’s style)
• Navigational software on a tablet or smart phone (We use Navionics)
• Paper charts
Hand Held VHF radio
• Spare Anchor and Rode
• Dingy repair kit
• Sail repair kit with some sticky Dacron

Regular Spares

• Water pump service kit – domestic
• Water pump service kit – other, shower, head etc.,
• Spare key, boat and any locks
• Water filters, house and water maker

Full Spares inventory

• Domestic water pump
• One spare water pump for other systems
• Critical electronic components, many modern electrical panels are susceptible to electrical failure in lightning storms
• Spare relay for windlass/electric winch if loads are high
• Spare generic filler cap for water/waste/fuel
• Water filter inserts
• Water maker filters and spares
• Spare block, shackle/rope shackles
• Ancor style electrical connectors, wire and crimpers
• Snatch block 
• Block and tackle

Engine/Generator/Outboard spares as appropriate

• Fuel filters
• Fan belt
• Oil engine/gearbox/saildrive
• Coolant
• Raw water pump impellor
• Hydraulic fluid/Autopilot drive

Normal Spares

• Raw water pump impellor overhaul kit and gasket
• Raw water pump seals and wear plates
• Selection of hose clamps
• Oil filter
• Spare key
Full Spares inventory
• Starter motor
• Alternator
• Fuel injector
• Spare raw water pump
• Engine water hose set
• Gaskets for exhaust elbow and raw water pump
• Anodes for propeller, saildrive and generator
• Saildrive seals if applicable
• Service/parts manual for each engine

Now we have an idea of the types of things to carry let us suggest a couple of other useful tips. 
• Where do we store all this stuff?
• How do we find it when needed?

We use clear to semi-clear plastic bins that are numbered. Where possible, items that relate to one another are stored together – engine parts with engine parts etc. Most importantly we keep a record of the number of the box and it’s contents on a spreadsheet and we do keep part numbers for common items also. This becomes especially useful when trying to order by phone or trade with another boater in need, for beer – see item at top of the list. We tend to store service items for the next maintenance event in the same locations, in that way I regularly have cause to go into the boxes and check contents. As a matter for another article, I keep ships records and many other useful information on the same spreadsheet.

There are too many permutations to determine an exact spares package but a general understanding of how your boat systems operate will help determine the likely failures that will need to be overcome, however with a little planning and forethought most breakages or component failures can be managed until repairs can be done properly.

Our thanks to the Catamaran Guru Brokerage team for sharing their thoughts! Martin, Stephen and Terry. 

Tell us what spares you have onboard!


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