Hi,

We've got a steel hull houseboat. Recently we pulled it
to work on the outdrive, and when it went back in it
began leaking. Swimming under the boat I found that
about 2" of a plate weld has rusted and cracked. The
inlet for the toilet's water is right beside the leak, and it
looks to me like the hole in that location weakened the
weld, so the stress from being on the trailer was enough
to crack it.

Most of the rest of the bottom looks in pretty fair shape,
though it will need to be pulled and at least painted
before too long. Can anyone suggest a good way to
temporarily plug the leak for a while? Is there anything
that can be applied under water, but won't be too hard
to remove later when the boat is pulled and fixed correctly?