It belongs to the Minerva collection and has been exhibited in a couple of their shows.
It is a very striking design and made from a very thick material. It almost looks like sailcloth. When Philip Sykas was giving a talk at Minerva on historical fabrics, it was brought out of storage for him to examine and he identified the material as worsted wool. More details here.
Here you can see the reason for the name of the quilt. It came from the Pembrokeshire area of Wales which has a strong maritime connection.
Possible crab claws here.....although someone who has also studied this quilt thinks they may be a flower patternAnd you can see why, because set in the four triangular taupe pieces and facing in towards the quilt center, are these flowers in pots. Sorry, it is difficult to visualise the position from this photo.
This gives you a better idea, you can see two of the plant pot designs here.
The running cable design here may represent the ropes used on fishing boats. There is a set of four crab claws in the corner between the thinner cable.
The thickness of the material means the quilting lines have an engraved look to them, almost as if they were carved from the material.
The quilter must have had calluses on her finger tips like saddle leather!