#876: Troutboard

Remora or sucker fish usually attach themselves to the bodies of larger, seagoing creatures in tropical waters. They have also been known to cling to small boats.

Today’s invention involves massively scaling-up this behaviour.


Given that the fish are highly streamlined, the approach is to arrange that they attach themselves, in large numbers, to the hull of a ship travelling in warm seas. This would result in a potentially large improvement in the thrust-to-drag ratio for very large seagoing vessels (since the extra form drag caused by adding a layer of such fish to a big vessel is tiny and yet they do each provide some extra propulsion).

This source of extra drive could be powered simply by providing a stream of waste food particles via hoses hanging from the prow. It also has the advantage of reducing the many causes of marine fouling which coat the undersides of ships.

If necessary, the fish could be contained within wire cages attached to the hull, in order to stop them jumping ship and to protect them from predators.


  1. Except I don’t think such riding fish provide any propulsion–they are attaching themselves so that they don’t have to swim around, in addition to getting nourishment from the crumbs. So since the attacher is just freeriding, isn’t this just drag and no propulsion?


  2. You may be right Tom. I thought about this for a while before posting. I believe that for a host fish, comparable in size to the suckerfish, the sucker creates a lot more drag than thrust. On a ship however, if you can coat a large fraction of the hull in sucker fish, their total effect on form drag is negligible and their contribution to skin friction drag may actually be to reduce it (by providing a grease-like coating). Since these fish do generate some small forward thrust each, I think it’s possible to use huge numbers of them as an additional, minor source of net propulsion, powered only by organic scraps.

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