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See this blog from ANZOR Australia for a succinct explanation of stainless steel use for keelbolts. It also applies to use of stainless steel generally in saltwater.

https://www.anzor.com.au/blog/keel-bolts

The New Zealand Hydrographic Authority (NZHA), located within Land Information New Zealand develops the official NZHA charts used in New Zealand. Electronic versions of the paper charts are available from the NZ Mariner service free of charge. They are electronic scans of the paper charts. They can be used on compatible software and are updated regularly. However LINZ has advised that the NZ Mariner service will be withdrawn soon and replaced with S-63 ENC charts.

The replacement ENC charts are updated fortnightly. This is a great service. It is feasible to have a full catalogue of the official NZ charts for the areas required kept on your vessel’s computer or a laptop.

The NZ ENC has a dedicated website https://www.encservice.linz.govt.nz/

The ENC charts require compatible software or hardware to run. They work well on small sailing craft in conjunction with an on-deck plotter running one of the proprietary charting solutions that come preloaded, as an ap or on an SD card.

The ENC system can be used on a PC or MAC interfaced with onboard electronics as the solution for primary information. Examples of use for the ENC charts include information on restricted areas, anchoring restrictions, AIS marked features, course planning, routing, yacht racing, AIS overlay, possibly radar and other electronic features. The on deck system is the one to use for immediate navigation, consisting of a waterproof plotter, or IPAD/Tablet with proprietary CMAP/Navionics type charting.

To run the ENC charts you need to obtain permits but these are either not expensive or free (LINZ). You get them from the charting software vendor and LINZ. Figure this out by following the LINZ and charting software provider instructions carefully.

Free software options include qtVlm or Open CPN. Paid software that will run it includes Expedition. The software will often also allow you to use other types of charts to such as third party or the raster charts that are being phased out in New Zealand.

A good source of information that should answer most questions is David Burch and you can find his blog here

The basics of how it works in New Zealand

If you want to buy a second hand boat we recommend that you get a survey (meaning boat inspection) done by a good surveyor who is independent of the seller or broker. Problems found after the deal is finalised can damage your bank account and spoil the fun of the boating. On the other hand if your survey or other advisors identify the issues you can negotiate or walk away if it’s a lemon.

Boats over 30 years old will usually require a survey for insurance purposes. You’ll need insurance to be accepted to rent a marina berth and possibly a mooring or to be hauled out at a boat yard.

You can either buy a boat privately (seller sells directly to buyer) or using a broker.

Brokers operate in the same way as real estate agents where the seller pays them a commission if they sell the boat. Brokers will almost always insist that you get a survey so that you are aware of any deficiencies and also so that they are not liable for them.

If you use a broker they will negotiate on behalf of the seller to get a deal acceptable to buyer and seller. The normal process is to make a deal conditional on structural survey which includes out of water internal, deck inspection and essential component checks, engine check, rig check in some cases if a yacht, and sea trial.

The structural surveyor does the hull and structure and external machinery inspection. A mechanic/engineer does the running condition of the engine. A rigger does the rig check aloft if required. A time frame is put on fulfilling these requirements and it’s a good idea to allow a little extra time to get the checks done as organising the surveyors, boatyards and other logistics can sometimes take longer than expected.

The deal becomes unconditional when you agree the conditions have been met to your satisfaction. Some deals have clauses to make it hard to get out of a deal such as that there must be substantial deficiencies. The surveyor’s report is typically used to quantify the deficiencies and it is common for there to be price reductions to alloy a buyer to have deficiencies remediated or for the seller to agree to repair the deficiencies. The broker negotiates these things.

Many people buy privately. A good approach is to use a written agreement between buyer and seller and work through the above processes of survey/checks directly between buyer and seller.

Regardless of what happens you will be in for a journey when you buy a boat. We hope it’s a good one.

Older timber boat components such as handrails, timber coamings, hatches, hulls and decks can sometimes be reinvented using epoxy and glass fibre.

The original component can be used as a mandrel to glass over encapsulating both sides. Or the component can be first structurally strengthened then sheathed with glass epoxy as a protective sheathing layer. Using a combination of the above is most common.

Teak handrail example project

Photos of a teak handrail encapsulation are shown below. The teak still has some strength so was used as a mandrel (former). The glass reinforces it to make it stronger than when new and keeps it dry.

Background: Teak is durable but soft, it wears away as can be seen on overlay teak decks. In this case the handrails diminution had been reduced to the extent that it could potentially break if given a decent heave. The teak plugs covering the fastenings were falling out exposing the countersunk machine screw heads. The rail was about 2/3 of its estimated diameter and the teak had ingrained mould in it.

Points to note that apply in all cases:

• Timber must be dry below about 16% moisture content
• Timber must be sound enough to hold fastenings
• Timber surface must be clean of mould and abraded
• Avoid dark finish colours that draw heat causing movement. Movement often leads to cracking and moisture ingress

Application: This article applies to well-engineered and built carbon fibre “spade” rudders hung independently of any skeg or the stern.

Advantages of carbon fibre composite rudders

Composite rudders and rudder stocks are constructed from a “composite” structure consisting of resin, reinforcing matrix and core. The main structural reinforcing matrix is often carbon fibre (carbon) although there are some heavier non carbon examples sometimes found.

The main structural shaft part of the rudder is the stock. Stainless steel (316 grade), or alloy (aluminium based alloy) rudder stocks have many disadvantages compared to carbon. They are typically much heavier, often twice the weight, corrosion prone and are difficult to seal at the penetration of the rudder stock into the rudder blade.

On the other hand, carbon composite structure for rudders has many advantages: The strength of carbon fibre offers design/engineering possibilities not possible with stainless or alloy. Same size like for like rudders can be much stronger/more durable. Thinner higher aspect ratio lower drag performance shapes can be used. The modern America’s cup boats showcase this attribute astonishingly, flying on rudders and foils over the water at 50 knots plus. Carbon rudder stocks are typically rectangular in sectional shape. The stock structures can be easily built with fibre layers tapered to the match the varying loads in different parts of the rudder. For example the greatest wall thickness will typically be at the highest load point, at the bottom bearing where the stock exits the hull. The laminate thickness in the rudder stock walls will taper towards the top bearing and bottom of the stock buried in the blade.

Carbon rudders are reliable for all vessels if engineered and built appropriately. There are few water ingress issues because the composite blade/stock becomes a one-piece structure when bonded together . Even if damaged, the materials – such as closed cell PVC foam and resin impregnated carbon fibre – are not water absorbing so can usually be dried and repaired if damaged.

Note: carbon should be isolated from the other vessel structure, and this can be done by using plastic type bearings.

What’s required to order a custom carbon fibre rudder?

If the rudder is a replacement for a previous stainless steel or alloy stock it may be beneficial to reconsider the blade profile (side on) shape and chord shape as carbon presents new opportunities. Other technological developments are likely to have occurred such as in rudder bearings. Any performance issues identified may be addressed such as blade balance, weight on the helm etc.

Steering systems related to the rudder stock and blade will also need to be replaced or systems modified which again is an opportunity to update/optimise as part of the process.

• The bearings and rudder tube
• Gland or hull penetration sealing system
• The tiller head system (if fitted)
• The attachment systems on the stock for the steering quadrant or tiller and autopilot tiller (if fitted)

Carbon rudder design/specification process

Information gathering

• If possible, obtain original vessel drawings including rudder and steering system
• Check the as built detail onboard and take photos
• Note any issues with the existing/prior rudder/steering system/vessel directional behaviour
• Note any preferences for bearings, gland sealing type

Initial specification

• Discuss plan with suitably experienced designer/Naval Architect and obtain price for design estimate to do the work excluding the structural laminate specification. Note that the laminate specification may be provided to the designer by a specialist composite engineering company, depending on whether the designer is also a structural engineer or not. The design work may or may not include specifying the bearings.
• Brief the designer to carry out the following initial design work to enable discussions to take place with a builder.
  • review information
  • prepare preliminary drawing of profile/planform of rudder and approximate top and bottom chord lengths, widths and section and position of rudder stock. This would include amount of blade balance, blade area in square meters old vs new.
  • Bearings
  • Approx. /sketch level detail of tiller head and steering quadrant/tiller clamp details and requirements.

Builder engagement

• When prelim work is complete, discuss with suitably qualified builder/s to obtain estimates for construction of blade and stock.
• Discuss modifications to steering system with builder and builder preference regarding composite laminate engineering, bearings, glands/gaitors, sealing system, and if possible estimate for the work required in addition to the blade and stock construction in order to remove old rudder and bearings, fit the new bearings and rudder, steering and commission on board.

Finalising project spec

• Designer/engineer complete working drawings and specification incorporating any builder/owner input, to agreed specification and fee.
• Builder and owner agree price estimate, time for completion and tolerances/standard of finished product and scope (i.e. is it complete turn key or just the components for owner fitting).

Note: engineering could be in builder or engineer contracts.

Composite construction process

Different processing methods can be used depending on budget and time. If cost is no barrier, then female composite moulds can be made from computer cut (CNC) male plugs. This way accuracy can be assured to a fraction of a millimetre as the finished dimensions will be as per the moulded surfaces. Alternatively female moulds can be milled directly in a stable board type material and the rudder blade and stock shells made from the sealed and painted moulds. Americas cup foils would be likely to use this type of technology when possible, to assure the dimensional accuracy where at very high speed any inaccuracy may be significant and can be amplified.

However, a more cost-effective processing method, and my usual preference for one off custom rudders is to male mould the stock on a stiffened foam mandrel and hand plane the blade to shape out of closed cell foam. The rudder stock and blade core are usually constructed separately. Then the stock is fitted and glued into the blade before the blade shell is formed by glassing over the stock and foam blade assembly. Then the blade is coated in fairing filler and planed/faired with the aid of templates. Accuracy of less than 1mm can be achieved by a skilled builder.

Composite engineers should specify the laminate stacks including thicknesses so the mandrel and foam blade dimensions can be calculated/checked by the builder.

It is useful to also fit and mill the built-up areas (build ups) where needle roller bearings will run on the stock on before bonding the stock into the blade. The milling can be done on a lathe. The build ups can be done later using stainless steel or custom GRP shells glued over but alignment will be more difficult and less precise. Solid GRP bearing journal shells/bearing finish will be better than stainless steel as they will not be prone to pitting/crevice corrosion. 

Note that self-aligning bearings are common such as those supplied by JEFA that we use and prefer. The system enables the plastic bearing race to be removed and replaced. However, it is important that the bearing shells on the stock are absolutely concentric as any difference will cause jamming/damage to the steering system. Self-aligning bearings will not help if the shaft journals/shells are not concentric.

Long term case study

I have built several composite rudders beginning with non carbon ones in the IMS Rule era and using various techniques.

The most recent examples completed were in 2012 for the Davidson 42 “Spitfire” to my planform, chord geometry, selected NACA 30% max thickness section profile, balance and steering system and bearing specification. The geometry also included a clamp on under deck composite tiller for autopilot and drag link steering connection. Engineering was specified by Gurit NZ office for the blade, stock and composite tiller.

We also built a similar rudder for the Young 11 “Force 11” in 2014 but was specified by the engineers who crew in her. We used JEFA bearings glued into a single tube from deck to hull.

Spitfire’s rudder is now almost 10 years old and has performed very well.

Processing summary

The processing for Spitfire and Force 11 consisted of:

• a male moulded stock using a foam mandrel vacuum bagged and cured in about 3 stages. The uni directional 0 degree carbon was interspersed with +/-45deg double bias carbon that was easy to lay and the consolidated thicknesses were well within specification.
• a male moulded closed cell PVC foam blade vacuum bagged
• Wet layup slow cure epoxies were used from Adhesive Technologies that were post cured to the resin specification.
• Carbon composites fibres were provided by NZ Composites.

The above processing was fast and cost effective and resulted in a very light/strong structure.

Bearings

Spitfire and Force 11 used JEFA plastic needle roller bearings and matched stainless steel sleeves for fitting on the stock. The bottom bearings were supplied by JEFA bonded into a GRP rudder tubes that were bonded in to the hulls. We had a custom made neoprene gaitor made to seal the rudder tube to the stock which is almost due for replacement after 10 years. An under deck nke autopilot is fitted on Spitfire.

Spitfire had wheel steering that has recently been removed and the vessel restored to tiller steering as the helm is light enough with the re designed rudder not to need the wheel.  The change necessitated a seal at deck level and another under deck gaitor has been fitted with a drain tube to the lower gaitor. This allows space for the composite tiller and autopilot ram to be attached and for the whole system to be watertight.

I designed and developed a new design tiller head system when the Spitfire rudder was converted to tiller. This was built using composite plate that can be supplied CNC cut and scaled to suit the tiller head size. Force 11’s tiller head has been simply done using carbon plate by her composite engineer crew members.

Lessons learnt

Spitfire was sold when her rudder was approx. 1 year old in 2013 and purchased back in 2020. Her rudder was removed in late 2020 for the first time to our knowledge, and the following was noted:

• Some pitting in the stainless steel bearing shells
• Some slight play in the bottom needle roller bearing, enough to rattle slightly when under motor with the 2 blade prop.
• Bottom gaitor slightly worn but serviceable

Having trouble setting up your nke gyropilot?

The nke gyropilot 2 can be adjusted in many ways, the defaults and auto settings out of the box aren’t right for every boat.  The following settings have worked well for us.

The base vessel was our Davidson 42 performance cruising vessel “Spitfire” which is approx. 13m LOA, with sailing length of 12m, weighing about 6,500kg. The design is very balanced with high stability.

Base set up minimum nke equipment recommendation for sailing to which this note applies:

• display unit
• Nke speed reference speed/depth box – required for wind calculations
• Nke wind speed/direction instrument
• Nke regatta or the replacement new 9x compass. These recommended compasses also measure heel and pitch and are not subject to card dip in the southern hemisphere. Note: The nke fluxgate is like a magnetic compass that will develop a dipped card in the southern hemisphere resulting in likely stickiness in its operation
• Gyrographic computer, rudder feedback sensor, electric/hydraulic ram package

Installation

Geometry: Install/check the pilot tiller and rudder reference sensor distances on the installation manual.

Compass: Check that the vessel’s magnetic compass/es are correct with less than 5 deg deviation on any heading. Install the nke compass in a location where there are no nearby computers/displays or large metal objects at approx. the widest part of the vessel. Adjust the installation heading to match the vessel compass heading and check on all headings to reduce the deviation to a minimum. Re locate if necessary. If there are issues, update to the latest firmware (we had an issue with the regatta compass that was resolved up a firmware update).

Only when the above had been done, perform an auto compensation if required.

Connections: Tin the wires and connect carefully as per the nke installation instructions.

Primary display: Set a multigraphic, or multidisplay at address 1 on the bus (if the installation pre-exists with a legacy older display).

Initialisation: Power up and initialise the pilot as per the nke instructions

Optimisation

The gyropilot 2 can be set on auto but we have found better results by adjusting the sensor inputs. The goal is to simulate a good helmsperson. Generally, a good helmsperson will have a smooth steady hand with slight movement in smooth seas and more correction required in rough conditions. We don’t want the pilot working back and forth like a saw, the least movement to keep the vessel on track is optimum. The main sensor inputs that affect the performance are: Compass damping, rudder coefficient, counter rudder, wind damping and gain. When the auto settings are de selected on any channel the gain setting has less effect.

Before getting started, read the section in the multigraphic/multidisplay “Multigraphic operation with the Gyropilot 2 processor” this will provide an overview. Don’t worry if you can’t remember it all.

Now; go into the sensor menu and adjust the compass input sensor

Hint: to get to the main page menu press and hold the page button, then scroll to the “sensor” menu. The below are found in the sensor menu:

Compass: Select magnetic heading > damping, set at approx. 15 – this can be adjusted to a lesser setting for more reactivity.

Next go to the Autopilot menu to adjust the settings

Hint: to get to the main page menu press and hold the page button, then scroll to the “autopilot” menu. The below are found in the autopilot menu:

Rudder coefficient: Select Pilot setting > rudder coefficient, set at somewhere around 8 to 15 initially a bit higher for a very high-performance vessel or higher speed. A higher setting will be more responsive (such as may be required in rougher conditions). When motoring or sailing in smooth conditions reduce the setting if the helm is moving excessively (sawing back and forth)

Counter rudder: Select Pilot setting > counter rudder, set at around 2 to 4 initially, there should be less counter rudder than main rudder as vessels are designed to have a tendency to round up to weather (weather helm), however some vessels may develop lee helm in some situations which can be countered by the use of counter rudder.

Wind damping: Select Pilot setting > wind damping, set at around 6 initially (on a scale of 0-9). The higher the number the more dampened the effect.

Improve boat sale prospects

The pre inspection survey/inspection is one of the key hurdles to be crossed when selling a second hand vessel. We often find many minor things wrong that could easily have been fixed. Or the owner, broker and purchaser all discover unpleasant truths about the vessel that with forewarning could have been corrected.

A pre sale survey can identify the issues. With this knowledge the sale process can be planned by either repairing the faults, mitigating issues or adjusting the price at the beginning to get the maximum interest before the listing goes cold. This can save all parties time and grief. Examples of things easily fixed  include:

• non ventilated boats with excessive condensation
• water in the bilge, oil in the bilge
• lockers full of personal stuff making the vessel difficult to inspect, and makes the vessel seem small
• rusty gas bottles
• rusty hose clips, especially on salt water intakes, holding tank and toilet hose clips
• Hose clips on systems connected to underwater through hull fittings that only have one hose clip instead of two on connections
• seized or semi seized salt water valves (through lack of operation)
• leaking toilets
• rusted anchor chain
• non functioning bilge pumps
• insecure bilge pumps
• loose stanchion bases
• bent stanchions
• chafed lifelines connection lashings
• stainless fasteners weeping rust from being surrounded by wet structure – potentially leading to crevice corrosion of the fasteners (to fix: remove, dry, replace and reseal)
• wet anchor lockers without ventilation leading to windlass rusty motor, and corroded electrical connections
• sliding hatches without stops (unwary new owners may pull the hatch open and find it keeps going over the side).
• expired flares
• rusted up emergency steering equipment
• plastic deck hardware that has degraded badly in the sun (i.e. aerials, plastic sheaves on blocks, plastic nav lights)
• loose/missing screws on beltings that can be replaced easily
• damaged beltings
• poor condition antifouling
• rusty or corroded mechanical parts such as engine mounts, and steering gear that has had salt water leaking on to it – best if you can find the leak and remove rust/corrosion and prime
• mouldy running rigging and canvas work, remove clean in the bath and replace
• mouldy tops of flying bridges

Addressing the above things is likely to help to achieve a clean survey report and a fast sale.