It has been many months since I have had time to update this webpage, thank you for holding on.
We have been busy with a large design project for a previous client. I will be posting details of this in the coming month.
Also we are making some changes to our business model – at the prompting of a couple clients. We are now offering our models built outside of New Zealand. This has been bought about by the distance we are from the larger markets and the massive disadvantage we now face with the exchange rate which marks the NZ dollar at historic highs against all major currencies.
Over the past year we have renewed and established new links with yards in Europe, North America and Asia which allows us considerable capacity while being competitive in the “semi custom” market, something that is always difficult to achieve. Check our new WATSON PROJECTS button for more details.
There is also a new button: FAQ. Over the years I have been asked so many questions, many being the same ones repeated. I am sure this part of the site will be popular as any question ever asked is always treated with a carefully considered answer.
So, to continue with our discussion on the W54 project………
W54 WHEELHOUSE ARRANGEMENT
If there is one discipline in naval architecture on which success rides the most, it is the proportions and detailing of the superstructure and deck fittings. Nothing destroys the aesthetics of a potentially great boat faster than a poorly designed superstructure.
Hand in hand with superstructure design is interior accommodation arrangement and the interior is all about (or should be) that demon, ergonomics.
When considering the wheelhouse arrangement there are three main points to consider:
Beginning with visibility we have found that “all-round” or 360 degree is of vital importance. To achieve this, the helmsman needs to be in an elevated position – which means that the wheelhouse needs to be elevated above other accommodation areas. The photo below shows an extreme example of this:
This harbour tug of our design from approx 20 years ago provides a demonstration of 360 degree visibility that includes a line of sight right around the deck perimeter. This is important on a working vessel; crew safety must always be considered where line handling is measured in Tonnes of breaking strain.
So important was visibility to the client that a mock up of the wheelhouse was built to fine tune the details. Note the size of the windows – for these we designed a custom aluminum extrusion to carry the weight of the ¾ inch glass.
Common to commercial craft is to make the wheelhouse as small as practical, which makes the requirement for visibility considerably simpler.
We do not need to go to this extreme for a passage maker. However we do need to demonstrate 360 degree visibility and we do this by completing a “Field of Vision” study.
In the example above the diagram demonstrates the line of sight from the helmsman’s position fore and aft and athwartship.
The diagram above demonstrates visual obstructions. These are for the main part the effect of the window mullions. This is the helmsman seated with his head in a fixed position.
Then in the diagram above we demonstrate the effect of the helmsman standing and with no more movement of his head than 100mm or 4 inches to give clear vision.
Then we have the question of access, particularly when coming alongside. We always provide bridge wings in our designs with port and starboard doors opening out to these. This allows the helmsman to step outside the wheelhouse and check along the ships side fore and aft – very helpful in a tight maneuvering environment. Also it allows easy access to the fore deck for line handling and we fit a bollard on the bridge wing for the aft spring line which allows the helmsman total control if berthing the vessel on his own.
The wheelhouse is elevated from the rest of the accommodation areas providing a separation from the other communal spaces; the saloon and galley, apart from visibility this is important as it allows these areas to be used at night while steaming. Lights can be on in the galley for making coffee etc without backlighting interfering with the helmsman’s vision.
One thing to avoid at all costs is double access; the forward accommodation accessed via the wheelhouse. This creates too much unnecessary traffic and destroys the ergonomics of valuable space.
Then we have protection, possibly the most important aspect over all others. Green water is the most dangerous for any vessel. One of the essentials is that the vessel can withstand the pressures that it may be subjected to in a seaway. Also that it has the ability to “shed” or shake off any green water that may congregate on deck.
For pressures we generally work with 1.5 Tonnes per square metre on the fore deck of the vessel. We also allow for freeing ports that will discharge these quantities as rapidly as possible; we calculate the time it takes to do so. These pressures and freeing port sizes are derived from internationally accepted rules that are the result of studies into the loss of shipping – not something we really want to go into detail here. The pressures are less in other areas of the decks and superstructure however for the front of the wheelhouse we allow for 1.0 Tonne per square metre. To offer further protection we include a Portuguese bridge. This lessens the impact that the front of the wheelhouse may be subjected to. One of the main considerations for this is the glass windows. It is our preference to exclude as much as possible any green water from impacting on glass. It is not that we use thin glass, in fact the glass to the front of the vessel is 30% thicker than elsewhere, but as a structural material glass can be unreliable.
The Portuguese bridge and bridge wings allow for a protected deck around the front of the vessel. This means that the helmsman and crew can safely leave the security of the wheelhouse to check the outside of the vessel or gain a better look out to seaward.
This now brings us to the arrangement of the wheelhouse. There are some essentials:
A comfortable helm seat – absolutely essential
Chart table with drawer – I know, everyone use chart plotters so no need for a chart table – wrong. Chart plotters are wonderful but given to inaccuracy. This will change over time, but any vessel should carry corrected, up to date charts.
Compass – magnetic. This is as necessary as ever as it should always be possible to take a bearing from a reliable corrected compass.
A console with electronic navigation equipment and machinery controls. This should be laid out so all is easily viewed by the helmsman and kept lower that the bottom of the windows so as not to obstruct vision.
Then there is one other consideration. The wheelhouse is one, if not the most important social area on the vessel. It is surprising how many people can fit into such a small space to enjoy the conversation and outlook. So there must be seating and a table. We like to make comfortable space for five seated plus a day berth which is usually the best reading space when out at sea.
Given the above it is to be expected that there is a similarity in the layouts of our models. This has come about over the design of many power craft and learning what to avoid rather than what to include.
Last Updated (Monday, 07 July 2014 20:38)
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