CaptLoyd you should see how much mess a sand blast unit can make when its being used. Sand is typically under a 150psi pressure and just goes everywhere along with all the old paint
and rust particles.
I have been thinking how Malds can sand blast those deck
beams and hull
join without making a mess. I was imagining laying down some heavy canvas
tarps inside the boat
an maybe making a plywood
box that can be clamped to the each beam as it is blasted. The box is not so much to catch sand (LOL) but to deflect the sand blast stream of sand from directly aiming into the interior
You really need to get those beams and hull
join to a NACE 2 Near White standard if you want a job that is going to last a long time. Grinding is just not going to achieve the same result. You could maybe grind the beams and then use that mini blaster I suggested to blast the welds and areas you cannot get clean with the grinder. I have seen reasonable results done that way.