Kit_L
Senior Member
- Joined
- Mar 12, 2016
- Messages
- 476
- Location
- Australia
- Vessel Name
- Suu Kyi
- Vessel Make
- Custom 40' catamaran
An update on the maiden voyage of Sea Biscuit, transiting from Woongoolba, Queensland (halfway between Brisbane and the Gold Coast) and Greenwell Point last week.
First, the vessel. Sea Biscuit is a 12.0m Cecil Boden-designed full-displacement crayfish boat, influenced, we are told, by the Sharpie design approach (relatively sharp entry, with the deadrise flattening along the hull to the stern, which is almost flat). SB has a 1.2m draft only, and a 4.3m beam; more on the pluses and minuses of this design below.
She is fitted with a reconditioned from the factory Perkins 6.3544, 120hp, and an 8KVA Sea Wasp genset (not in use) where the fishwell would otherwise be.
She has two 625 litre fuel tanks in the aft compartment, about 0.5m in from the stern, and going forwards ~1.5m. She carries 350 litres of water in a poly food-safe tank, in the genset compartment, port side.
We left Horizon Shores Marina at 10:20 (Qld time) Saturday, and crossed the Greenwell Point bar at midnight exactly, Monday night, EST. Recall that this is a 1,100km journey by road...
Adrian (co-pilot) and I alternated 1.5–2 hour shifts for the whole period. The sea is a very large (and surprisingly crowded) place at night. We steamed 24/7 for the trip, and mostly 20–40nm offshore; more on this below.
By water, the passage was 550 nautical miles. Here are the raw stats, complied by the "Land Captain", Greg Laughlin, who kindly was giving us 8-hourly weather updates via an InReach satellite-phone-accessing device:
Distance travelled: 550nm
Time: 62 hours
Speed: 8.9kn. This is an amazingly fast average for a single engined, full displacement, 15 ton Sharpie-design fishing trawler—did we somehow breach Froude's number?
No! Captain Adrian was able to find the East Australian Current (EAC) for most of the trip, by finding the edge of the continental shelf. Often we were 35+nm offshore: no land is visible at these distances from our boat. Port Kembla's steel-making stacks can be seen 20+nm offshore, though.
Sea Biscuit's pushed-to-the-theoretical limit on flat water 'hull' speed is 8.2kn, but no one would run her at that speed, because as everyone here knows, fuel consumption increases dramatically as you approach this limit and you sit in the trough of a wave. Instead, we loafed along at only 1,250rpm on the engine—in flat water, this moves us wake-free (because there's little drag at this speed) at around 7kn. By finding the currents, we occasionally saw 11kn on the Speed Over Ground ("SOG") display on the GPS, and 9.5–10kn for long periods. Free speed. Had we travelled back without the current, hugging the coast as many do, we would have taken 80 hours instead of 62.
Course changes were frequent: we have an active AIS fitted (as well as a new technology radar) and we are able to see all ships similarly fitted. Commercial ships must have these. We saw many freighters, ore ships, container ships, and one Navy vessel. Many were steaming North. Our system detects vessels at 36nm range; we watched and waited, and made small course adjustments; most of the time they made reciprocal adjustments; this was lovely to see (and anxiety reducing, too!). We had our "alarm guard" set for the maximum (2nm on the Garmin; 4nm would be nicer); only two vessels (out of approximately the 30 we "saw") came slightly inside this limit. They were most certainly visible then; one was a massive cruise ship, lit up like the biggest Christmas tree you've ever seen!
Olivia, my partner, had pre-prepared a large amount of food (kept in a 50 litre icebox on the rear deck), but the boat movement was extremely fast (we were crossing small and medium waves, as well as the ground swells (we had three interacting swells on one night) relatively quickly; this makes the boat react with vertical and horizontal accelerations—these are felt strongly. All this meant that we had to eat things that we could stop moving (a sandwich or a bowl). This is one of the disadvantages of the flatter, relatively shallow draft design: less roll than a round bottomed trawler, but significantly faster roll accelerations, too. As well, the pitching pivot point in this design (given engine and fuel tanks placements) is about 2/3 along the hull; this means an easy movement in head seas, but a lot of bow movement, rendering the forward cabin unusable.
To cross the cabin floor, for example, needed anticipation, at least one hand gripping solidly, and great care. We could not drink any alcohol (the short shifts prevented this) and sleep was not possible, but my meditation background helped immensely here. Adrian was surprised to find that I needed a lot less sleep than he did (not that he was getting any "sleep!"). Our energy levels and attention stayed high using this approach.
I had a salt water bath out on the back deck a few times; this helped stay clear and focussed, too. Even getting a half bucket of sea water (via a bucket and tied-off rope) was fraught at 7kn: if you are not careful, the bucket will be ripped from your hand!).
We did not use the forward cabin after Adrian's first attempt: the vertical movement of the bow meant that his leg were hitting the ceiling on big waves! We both napped in the main cabin; I will take some picture of the interior and post later. The bunk we used is well behind half the length of the boat, and with this design and weight distribution, bow movements are far greater than stern movement. The wheelhouse bunk was a relatively comfortable place to rest.
Last point for today. We filled the diesel tanks before we left and we still have about half left. This means that we used about 1.1 litres per nautical mile; very satisfying.
More to come.
First, the vessel. Sea Biscuit is a 12.0m Cecil Boden-designed full-displacement crayfish boat, influenced, we are told, by the Sharpie design approach (relatively sharp entry, with the deadrise flattening along the hull to the stern, which is almost flat). SB has a 1.2m draft only, and a 4.3m beam; more on the pluses and minuses of this design below.
She is fitted with a reconditioned from the factory Perkins 6.3544, 120hp, and an 8KVA Sea Wasp genset (not in use) where the fishwell would otherwise be.
She has two 625 litre fuel tanks in the aft compartment, about 0.5m in from the stern, and going forwards ~1.5m. She carries 350 litres of water in a poly food-safe tank, in the genset compartment, port side.
We left Horizon Shores Marina at 10:20 (Qld time) Saturday, and crossed the Greenwell Point bar at midnight exactly, Monday night, EST. Recall that this is a 1,100km journey by road...
Adrian (co-pilot) and I alternated 1.5–2 hour shifts for the whole period. The sea is a very large (and surprisingly crowded) place at night. We steamed 24/7 for the trip, and mostly 20–40nm offshore; more on this below.
By water, the passage was 550 nautical miles. Here are the raw stats, complied by the "Land Captain", Greg Laughlin, who kindly was giving us 8-hourly weather updates via an InReach satellite-phone-accessing device:
Distance travelled: 550nm
Time: 62 hours
Speed: 8.9kn. This is an amazingly fast average for a single engined, full displacement, 15 ton Sharpie-design fishing trawler—did we somehow breach Froude's number?
No! Captain Adrian was able to find the East Australian Current (EAC) for most of the trip, by finding the edge of the continental shelf. Often we were 35+nm offshore: no land is visible at these distances from our boat. Port Kembla's steel-making stacks can be seen 20+nm offshore, though.
Sea Biscuit's pushed-to-the-theoretical limit on flat water 'hull' speed is 8.2kn, but no one would run her at that speed, because as everyone here knows, fuel consumption increases dramatically as you approach this limit and you sit in the trough of a wave. Instead, we loafed along at only 1,250rpm on the engine—in flat water, this moves us wake-free (because there's little drag at this speed) at around 7kn. By finding the currents, we occasionally saw 11kn on the Speed Over Ground ("SOG") display on the GPS, and 9.5–10kn for long periods. Free speed. Had we travelled back without the current, hugging the coast as many do, we would have taken 80 hours instead of 62.
Course changes were frequent: we have an active AIS fitted (as well as a new technology radar) and we are able to see all ships similarly fitted. Commercial ships must have these. We saw many freighters, ore ships, container ships, and one Navy vessel. Many were steaming North. Our system detects vessels at 36nm range; we watched and waited, and made small course adjustments; most of the time they made reciprocal adjustments; this was lovely to see (and anxiety reducing, too!). We had our "alarm guard" set for the maximum (2nm on the Garmin; 4nm would be nicer); only two vessels (out of approximately the 30 we "saw") came slightly inside this limit. They were most certainly visible then; one was a massive cruise ship, lit up like the biggest Christmas tree you've ever seen!
Olivia, my partner, had pre-prepared a large amount of food (kept in a 50 litre icebox on the rear deck), but the boat movement was extremely fast (we were crossing small and medium waves, as well as the ground swells (we had three interacting swells on one night) relatively quickly; this makes the boat react with vertical and horizontal accelerations—these are felt strongly. All this meant that we had to eat things that we could stop moving (a sandwich or a bowl). This is one of the disadvantages of the flatter, relatively shallow draft design: less roll than a round bottomed trawler, but significantly faster roll accelerations, too. As well, the pitching pivot point in this design (given engine and fuel tanks placements) is about 2/3 along the hull; this means an easy movement in head seas, but a lot of bow movement, rendering the forward cabin unusable.
To cross the cabin floor, for example, needed anticipation, at least one hand gripping solidly, and great care. We could not drink any alcohol (the short shifts prevented this) and sleep was not possible, but my meditation background helped immensely here. Adrian was surprised to find that I needed a lot less sleep than he did (not that he was getting any "sleep!"). Our energy levels and attention stayed high using this approach.
I had a salt water bath out on the back deck a few times; this helped stay clear and focussed, too. Even getting a half bucket of sea water (via a bucket and tied-off rope) was fraught at 7kn: if you are not careful, the bucket will be ripped from your hand!).
We did not use the forward cabin after Adrian's first attempt: the vertical movement of the bow meant that his leg were hitting the ceiling on big waves! We both napped in the main cabin; I will take some picture of the interior and post later. The bunk we used is well behind half the length of the boat, and with this design and weight distribution, bow movements are far greater than stern movement. The wheelhouse bunk was a relatively comfortable place to rest.
Last point for today. We filled the diesel tanks before we left and we still have about half left. This means that we used about 1.1 litres per nautical mile; very satisfying.
More to come.
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