Hull Construction Question

[commander bill]

I understand that "Stringers" are used to stiffen the hull construction and otherwise help support decking and floor structures while boat is being built. On the R25 a pair of stringes appear to be constructed as part of hull and run most of length of hull. The batteries, Genset, water heater, & storage compartments are located directly outboard of these with main engine between the 2 stringers. Looking at hull from inside the engine compartment it is difficult to see where actual hull ends and stringer starts. There are several drain holes routed through the stringers to allow any water that might leak in those ooutboard locations to drain to the bilge. My questions are:

Are the stringers hollow?
Are they cored with foam or wood?
I assume it is OK to drill & place screws into them since the factory appears to do this with OEM attachments such as fuel filter.
If hollow could a stringer become a hidden trap for water? It may be my imagination but it appears that the "normal port list" on my boat gets more noticable later in the season after 6-7 months in the water. Then when placed back in water each spring the list is less noticable again.

 

[rt11002003]

Andrew, or some of the other folks at Ranger can answer specifics as to the R-25.

Generally, stringers forward and aft of the engine are hollow to lessen weight. However, coring adds strength and closed cell foam is light and is used sometimes in long runs of hull unsupported by bulkheads. If the engine is bolted to the stringers, it's a good bet they have enclosed wood to add strength for the engine mounts. My Albin had wood inside the fiberglass stringers in the engine compartment. If stringers are hollow and have weep holes drilled to allow water to get to the bilge there shouldn't be a problem as long as the holes are clear. This assumes the holes are drilled such that water can't get trapped.

Water can get into anything that has any sort of hole in it. And, it can get into fiberglass without a hole thru the process of osmosis. Osmosis can result in blistering and in extreme cases, delamination of the fiberglass layers. It can cause a boat to absorb a lot of water during a season. I've seen cases where sailboats absorbed several hundred pounds.

Drilling holes can be tricky. 😱 I only drill when I know what's on the other side. I've taken to glassing wooden blocks to the boat and mounting things to the blocks. I notice Ranger has used the same technique in my boat.

Gene

 

[commander bill]

Ranger has glassed wood blocks to the hull for much of the mounting done at factory but some items are drilled directly to the stringers. It is hard to tell where actual hull stops & stringer starts when observing from inside engine compartment since the stringers appear to be glassed to the hull. I am just concerned we may have a potential future problem if there is wood inside of stringers and they trap water. Unless I am imaging things my boat will settle some during season (port list gets worse) but there is no additional water in bilge or outboard compartments. I do see holes that allow drainage to bilge from outboard compartments but have seen none from stringers.