Bilge Maintenance in Flat Bottom Steel Boats

[Rumars]

If the bilges of a recreational steel boat contain anything else then dust bunnies, something is seriously wrong and sponging them is a concept for the far future when the boat is secure on dry land. Even condensation is something you shouldn't have to think about if the vessel is properly constructed.

A sailboat on inland or coastal waters must necessarily sail to windward simply because the wind and destination don't always cooperate. It's either sail, row or motor, and you have to decide what's important because that has implications on the design (rig size and placement, ballast, etc.).
As for electric propulsion and solar generation, it's simple, you have a fixed amount of panels, giving you a nominal instant power. Either you make due with that or supplement it via batteries or internal combustion. On a canal you don't need much to keep moving, it's different if you go uphill on a fast flowing river or against the wind or tide.

Yrvind's solutions for open ocean crossings are irrelevant to a craft your size, forget everything he's said or done.
If you want to raise a mast by hand you need serious counterbalancing for it, even if it's made from carbon fibre. Big lug sails are not something you want to handle alone, hence why the chinese divided them into panels and put miles of rigging on them. There are solutions for folding rigs, you just have to decide on the level of complexity you're willing to live with.

 

[Scow]

If the bilges of a recreational steel boat contain anything else then dust bunnies, something is seriously wrong and sponging them is a concept for the far future when the boat is secure on dry land. Even condensation is something you shouldn't have to think about if the vessel is properly constructed..

@Rumars Thank you for the feedback. I’m especially interested by your points about dry bilges in a properly built steel hull. I don’t have any experience with one myself and it seemed like the majority of input was that damp/wet bilges are inevitable. It’s a subject I now definitely want to understand better. I am particularly interested in design for reliability and the ability to maintain well and clearly both hull and systems. I want to be very mindful about design choices that could help avoid rust, rot, mold, failing sanitation pipes, failing electrical, leaking roofs, etc..

 

[Scow]

@Rumars and others. When I look at boats advertised for sale in Europe versus North America, USA in particular, it seems like steel hull recreational boats are much more common in Europe. I’m probably overlooking something obvious, but why is that the case?

 

[Rumars]

You insulate and ventilate. Insulation so there's no condensation and ventilation so air can move. The beauty of metals is that everything can be welded, there are no penetrations to seal, no screws to leak, etc. You buy the proper hatch, it gets welded in and when it's shut its airtight. That's the alternative to ventilation, having sealed of sections that are airtight, you drop in a bag of silica gel, close the hatch and forget about it until next time. With a configuration like you envision I would probably use both approaches, the low sidedecks as sealed chambers, and maybe also some of the foredeck (depending on exact configuration) also.

It's entirely possible to achieve dry bilges with any other boatbuilding material, it's just harder to maintain this state over time. I wouldn't expect any new boat to have water in the bilge, just as I don't expect a new engine to leak oil. If a traditional shaftseal is used I would install a proper driptray underneath it with its own very small pump to empty it regularly.

I can't tell you why steel hulls were more popular in Europe, I suspect there where just more yards with trained workers and good designers with influential boats. Even now, metal is a very attractive one off or small series material choice, altough Al is much more popular today then steel.

 

[Scow]

You insulate and ventilate. Insulation so there's no condensation and ventilation so air can move. The beauty of metals is that everything can be welded, there are no penetrations to seal, no screws to leak, etc. You buy the proper hatch, it gets welded in and when it's shut its airtight. That's the alternative to ventilation, having sealed of sections that are airtight, you drop in a bag of silica gel, close the hatch and forget about it until next time. With a configuration like you envision I would probably use both approaches, the low sidedecks as sealed chambers, and maybe also some of the foredeck (depending on exact configuration) also.

I like the idea of designing in some fully sealed chambers also from a safety perspective.

What are the one or two most effective approaches to insulating a steel hull? Any known bad ways to do it?

 

[Rumars]

Closed cell PU spray foam and self adhesive closed cell PE flexible sheet foam (Armaflex) are the two favorite insulation methods today for yachts.

The best and greatest ideea when it comes to keeping a steel hull from rusting from the inside is to have air conditioning. Since you're building a motorboat with plenty of solar there's absolutely no reason not to install it. When you don't need cool air you can run it in dehumidifier mode.

 

[gonzo]

If the bilges of a recreational steel boat contain anything else then dust bunnies, something is seriously wrong and sponging them is a concept for the far future when the boat is secure on dry land. Even condensation is something you shouldn't have to think about if the vessel is properly constructed.

In cold condensation is common. For example, in this area, the water can be 35 F (3C) and the air 85F with 90% humidity. In days like that the hull will be wet in the bilges.