raw water washdown system

[Sunbeam]

I'm kind of curious as to why holes through the hull is a bad thing.

So what's wrong with a through hull? Honest question. Assuming you use good bronze stuff.

I can give you my thoughts.

First of all, if good components are used and they are properly installed with high quality components (valves, backing blocks, connectors, hoses, clamps, etc.), I don't think there is anything wrong with a through-hull. But. There are components (even if they are the best money can buy), and no matter how good they are, they will always be more complicated and less reliable than no hole in the hull. In other words, while I am not one to avoid a through-hull at all costs, and while I think they are a fine thing if properly installed and maintained, I do also know that something that is not there to begin with can't possibly have a problem. Something that is there may be worth the risk, and the risk may be very low, but it is still a risk (I have happily put through hulls into my other boats when I wanted them; but I have also eliminated and glassed over ones I considered to be superfluous and/or changed those that were poorly installed).

To thicken the plot: Through hulls and associated hardware (hoses, clamps, backing blocks) are not always installed using "best" components, and, when installed into cored hulls the coring is often not closed out in what I would consider to be the correct way. In that case I would consider it a very undesirable liability (possible consequences ranging from wet core to de-bonding to sinking). Especially if there were another way to easily accomplish the same thing (e.g. washdown pump intake over the transom)

PS: This does not mean they are all this way, but I have seen photos of a through hull installed on a C-Dory that did not use best components, etc. I have also seen this on many, many other production boats, so it's not a knock on C-Dory especially.

 

[haliman]

When I spoke with Northwest Marine and was told they do the thru hulls in the same compartment that the bilge pump is in, the reason is they told me that little tray like area between the tanks where the bilge pump is mounted is all fiberglass on the boats they build. Since they did not build mine (2008) he was not sure. This is where I will do my thru hull. I trailer my boat so if anything were to fail and hopefully not, I will be on the boat. I feel confident I can do a great install. Again no expert at all but this is done all the time and like others have said if done properly with no shortcuts I think it's pretty safe. Thanks all!!

 

[Sunbeam]

When I spoke with Northwest Marine and was told they do the thru hulls in the same compartment that the bilge pump is in, the reason is they told me that little tray like area between the tanks where the bilge pump is mounted is all fiberglass on the boats they build. Since they did not build mine (2008) he was not sure.

On my 2002 22 Cruiser, that area - the depressed "sump" area in the center between the fuel tanks - was cored with balsa (wood). My guess would be that the majority of past 22's are that way (cored), but I wouldn't feel sure without checking an individual boat. I'm sure about mine because I personally removed that core and "closed it out" with solid fiberglass. Below I have attached one photo which shows the coring in the sump. There is additional info/photos in my "Sunbeam ~22 Cruiser thread" if you would like to see more.

 

[haliman]

When I spoke with Northwest Marine and was told they do the thru hulls in the same compartment that the bilge pump is in, the reason is they told me that little tray like area between the tanks where the bilge pump is mounted is all fiberglass on the boats they build. Since they did not build mine (2008) he was not sure.

On my 2002 22 Cruiser, that area - the depressed "sump" area in the center between the fuel tanks - was cored with balsa (wood). My guess would be that the majority of past 22's are that way (cored), but I wouldn't feel sure without checking an individual boat. I'm sure about mine because I personally removed that core and "closed it out" with solid fiberglass. There is some info/photo in my "Sunbeam ~22 Cruiser thread."

Thanks will take a look!!

 

[haliman]

Great info and pics!!!!!

 

[rogerbum]

I'm kind of curious as to why holes through the hull is a bad thing. All the boats I've had had through hull fittings, with valves. None of them ever leaked, though I had to replace a couple of Forespar Marelon valves ( composite reinforced polymer ) which froze up. And I did that with the boat in the water.

So what's wrong with a through hull? Honest question. Assuming you use good bronze stuff.

On Journey On, the washdown pump shares the through hull that services the marine head. Works great, the pump works as a shut-off valve both for the intake and outlet.

Boris

Here's one of many articles about why boats sink. If you look at the table under "Why Boats Sink at the Dock", you'll find that 50% of the time, the cause is due to an underwater fitting. As I said above, either way "will work if properly installed, operated and maintained". Of course, the 50% of the boats that sink at the dock are a small percentage of the total (e.g. most DON'T sink at the dock) so the odds of sinking only go up slightly with an underwater fitting.

Also, I'd bet $'s that most that do sink are boats with underwater fittings made of inappropriate materials (hardware store brass) and/or mixed metals in contact and/or old fittings and/or fittings without closed valves. So, if done correctly, there's nothing particularly bad about a through hull fitting. HOWEVER, ,any shops and boat builders will not do it correctly - particularly when going through a cored area. Many will just slap some 4200 or 5200 on the fitting and call it good. That will often work just fine, for awhile (maybe many years). But it will eventually fail and the core will be exposed to a little water. Unless you know the shop well and specifically specify how you want them to seal the core or do it yourself, I don't think you can count on it being done correctly. So if I can accomplish what I want without a through hull, I'll generally avoid the through hull.

 

[haliman]

So as far as sealing the core - My thoughts are using some West System epoxy inside the core wall, let it cure then install and seal with 5200. What is your take on this or ideas of better way. I want to do it right the first time.

 

[Sunbeam]

So as far as sealing the core - My thoughts are using some West System epoxy inside the core wall, let it cure then install and seal with 5200. What is your take on this or ideas of better way. I want to do it right the first time.

To my mind, there are a couple of "levels" to sealing or "closing out" the core. Well, maybe three. The first one I don't consider adequate, so I don't use it, but in order:

1) "Paint" edges of core with neat epoxy. Then proceed as usual (fit and bed hardware).

2) Remove core back a certain distance (depending on situation), prep, and then fill in with thickened epoxy. Then proceed as usual.

3) "Close out" core by removing it and then fiberglassing such that you bring the laminations together (so there is no "thickness" at that area - in other words you end up with a "dish" there as compared to the surrounding cored areas. This is the "ultimate" way, but I most often use #2 as ultimate is not necessarily always needed or wanted. I use this way for places below the waterline for sure, and would consider it for areas that will have sitting/standing water (normal deck fittings shouldn't have standing water around them, and I consider method #2 to be good for those). I would use this method for a through hull on a boat cored beneath the waterline, for example. I closed out the core in this way around the new garboard plug/transom drain shown above. It used to go through a "tunnel" of core; now it just fastens to fiberglass.

On production boats, the vast majority that I have seen install hardware into a cored area by just caulking, or at most "painting" the core with gelcoat, silicone ( :amgry ) or other substance. Anything else is an exception (and a good one!)