Concern for Broken Through Hull Fittings

[islavov]

[Moderator's note: two separate threads on the same topic for the same boat by the same author are combined in the original thread.]

Q1: should I be concerned about a broken through-hull below the water line and under the swim platform on my 2004 190 NANTUCKET boat?

I do not see any rotten wood. I am drying out the holes while waiting for new fittings to be delivered.

Q2: beyond the measures I describe above, is there any other action I need to take?

BACKSTORY

On my [2004 190 Nantucket boat's below-the-waterline through-hull fittings] I noticed there was a break in the fitting outlet below the water line under the swim platform (as was previous the topic of a long dormant thread from seven years ago].

I do not know know how long the through-hull fitting has been broken.

I first noticed the broken through-hull fitting when as part of a maintenance project I began taking off all-through hull fittings [on the 2004 190 NANTUCKET]. I began that project because two brass through-hull fittings in the engine [splash well] were weeping a brow watery liquid.

[FOR FURTHER VIEWING

If you want to watch about six minutes of narrated recording made about the fittings you can find them at the URL below:]

https://youtu.be/lhLWiFc2Y6U [Three minutes long with much hand held camera work with very rapid movement, this presentation describes the process of finding one or two cracked through-hull fittings.]

https://youtu.be/OKxWp4RvXbo {Three minutes long with much hand held camera work with very rapid movement, this presentation describes the condition of the hull surruounding the large holes in the transom after the five through hull fittings were removed.]

[jimh]

Q1: should I be concerned about a broken through-hull below the water line and under the swim platform on my 2004 190 NANTUCKET boat?

Yes. If the through-hull fitting is below the water line and is not intact and completely sealed against penetration by water, there is risk of water getting into the exposed wood reinforcement in the transom and into the interior foam of the Unibond hull.

I do not see any rotten wood. I am drying out the holes while waiting for new fittings to be delivered.

Q2: beyond the measures I describe above, is there any other action I need to take?

If you allow the areas surrounding the large diameter openings in the hull to dry, and any sign of water is then absent, and the wood appears to not have been compromised, then you should consider apply epoxy to all the exposed surfaces of the transom interior to completely seal them. You might consider sanding the inside of the hole to enlarge it slightly so when you apply the epoxy layer the ID of the hole will return to the original size. When you install the new through-hull fittings you should use a quality sealant--not some super strong adhesive--to bed the new fitting as they pass through the transom. You do not want a super strong adhesive because some day you may need to remove these fittings when they break.

To be sure all the moisture in the areas surround these large holes has been removed, you should let the drying process continue for as long as tolerable. It might take a month for all the moisture to evaporate. You can encourage that by passing warm air through the holes, as from a hair dryer on the lowest setting.

[Phil T]

The through hull drains are a achilles heel of a Boston Whaler.

You should be concerned.

Before you reinstall the new ones and after the inside is as dry as practical, use a hair dryer to ensure the wall surface of the hole is dry. Coat the wall of the holes with a polysulfide based caulk, Boat Life's Life Caulk. Do not use a hybrid adhesive-sealant.

Insert the new drain tube with significant sealant on the inside and ouside walls so that when you tighten down the drain, the sealant oozes out the edges.

Now you do not need to worry about a future failure.

Personally, for a 20 year old model, I would replace all the drains out of an abundance of caution.

[islavov]

[On my 2004 190 NANTUCKET ]the [embedded wood in the] transom is wet [due to failed through hull fittings.] [When] I drilled a mounting hole or a SONAR tranducer into the embedded wood transducer in the transom] water seeped out.

Fig. 1. Engine splash well brass drain with brown seepage.

IMG_6790.jpg (86.01 KiB) Viewed 354 times

Fig. 2. Red arrow points to broken plastic through-hull fitting on transom below water line.

IMG_6914.jpg (90.51 KiB) Viewed 354 times

Fig. 3. Red oval indicates the location of the below-waterline plastic through-hull fitting that has failed.

IMG_6916.jpg (92.6 KiB) Viewed 354 times

Q3: what other damage can expect to find?



BACK STORY
I bought boat exactly in September 2023, and since then have added 80-hours of running time to the engine (now at 450-hours). I have been making daily trips for angling in the upper Chesapeake bay.

In mid-Summer 2024, I started noticing brown water on a cockpit drain and engine splash well drain on Port. My driveway is slopped such that when I park the trailer, the port side sits lower.

After hauling out the boat after use, I'd park the boat and always wash and dry it. Then, after about two days of the summer heat, I began to notice the brown water seeping out. I immediately knew something is not right, and planned to repair all through-hull fittings in the coming off-season.

Also, for the first time in my ownership, the boat was left in the water of a lake while were were on vacation. I don't think this did damage.

I feel [the wet wood in the transom is due to] long term damage, but for some reason I did not noticed until the brown water seepage made me look closely.

Then I found a cracked through-hull fitting connected to 1.5-inch hose leading to livewell drain, with the crack occuring very near the outboard end of the fitting on the transom. I suspect as the hose shrunk through the seasons, it put pressure on the plastic thru-hull and it eventually cracked

I could pull the ring-portion of the cracked fitting with my nails and it literally broke off. There was sealant around the fitting but sealant was separated from the wood. I could pull the thru-hull easily from the inside.

The wood inside transom looked wet.

Then I removed the other through-hull fittings and the brass drain tubes from the engine splash well drains. All the through-hull holes were wet,

I setup a fan with flex duct to encourage drying. and let it blow air for several days, but progress (toward dry wood) was slow

I have been searching and considering all facts. I ams scared that I may have more damage [that may be] had to find

I drilled one of the transducer bolts hole deeper to penetrate through the outer fiberglass and go into the wood, and water seeped out.

Then I made two more holes lower in the transom and more water seeped

Wood is not rotten but obviously is soaked.


[Invites readers to watch three motion picture recordings to further their understanding the situation that he has explained in the narrative above.]

A two-minutes 40-seconds hand-held camera with rapid movement and shaking with off camera narration:
https://youtu.be/lhLWiFc2Y6U

A three-minute 5-second hand held camera with rapid movements and shaking with off camera narration:
https://youtu.be/OKxWp4RvXbo

A one minute handhed camera with very rapid forward-backward movements with off camera narration;
https://youtu.be/HEfvGvWaEuU

[jimh]

I have not watched any of the 13-minutes of your recorded presentations, as I felt your narrative and photographs gave me a good understanding of the problem. This problem seems to be a common occurrence with that particular Boston Whaler boat model and age. Some other threads have discussed this problem in prior posts.

You should read more at this seven-year-old prior discussion:

Through-hull Fitting Repairs c.2004 190 NANTUCKET
https://continuouswave.com/forum/viewtopic.php?t=2729

The thread has a very long and extensive discussion of this problem.

Also, you should watch the Boston Whaler presentation on how to make proper repair, available at:

Replacing a Thru-Hull
https://youtu.be/Zby76eoKO-I

Other similar problems:

1999 17 OUTRAGE II PLASTIC Through-hull Drain and Scupper Replacement
https://continuouswave.com/forum/viewtopic.php?t=5194

1999 17' Outrage: Replacing Thru-hull Fittings
https://continuouswave.com/ubb/Forum3/HTML/020900.html

[islavov]

Jimh--thank you for your responses and all the edits and clarifications on my initial write ups- it is very much appreciated.

I have seen the first link you shared (and will read the others) and it is a very relevant link. Yes, in fact, [it discusses the] same problems and solutions as I am faced with. I just wish I read that thread sooner and have done things preventatively.

I am following all your suggestions.

The best case scenario for me is to let the holes dry; seal around holes; and add new fittings and quality sealant.

Please review the third video I posted. I wanted to be certain of how much water is in there, and when I drilled one of the transducer bolts all the way through and then another test hole at the lowest point of transom I collected about probably 6 to 8-ounces of brownish water, and it was stinky especially in the beginning. I don't know how rot smells, but that smelled like rot to me. That concerns me, and I feel it might change the course of action. I am not sure how much this can be dried when it all closed up. Maybe drill more holes and wait longer.

Also:

Q4: is the transom a separate closed compartment [from the rest of the interior of a Unibond hull]?

Q5: could [seawater] have leaked into the foam of the hull?

I am hoping it is separated from hull the foam, but cant really see as the engine well is there in the middle and you cant really see the transom on the inside. I am trying to find out.

Q6: should I worry about water intrusion past the transom and into the hull foam?

[islavov]

The through hull drains are a achilles heel of a Boston Whaler.

You should be concerned.

Before you reinstall the new ones and after the inside is as dry as practical, use a hair dryer to ensure the wall surface of the hole is dry. Coat the wall of the holes with a polysulfide based caulk, Boat Life's Life Caulk. Do not use a hybrid adhesive-sealant.

Insert the new drain tube with significant sealant on the inside and ouside walls so that when you tighten down the drain, the sealant oozes out the edges.

Now you do not need to worry about a future failure.

Personally, for a 20 year old model, I would replace all the drains out of an abundance of caution.

Thank you, Phil!

Did you see the third video - my transom is wet all the way though the bottom, and it leaked a coffee cup of light brownish smelly water when i drilled a small test hole at bottom.
Closing things up is the easiest to do, but I feel I should either treat it more inject penetrating epoxy and things like that (so many options when you start reading).
Or, close it and start saving for a full transom repair in the near future. Question is how long?

[jimh]

The presence of a brownish liquid with some odor associated that comes out of an empty fastener hole from the interior of a Unibond hull is most likely the result of some uncured laminating resin, probably polyester resin, mixing with water.

[jimh]

Q4: is the transom a separate closed compartment [from the rest of the interior of a Unibond hull]?

No. The transom wood reinformacemnt is placed into the hull mold during the lay-up of the hull. The hull liner is created in a second mold, in a similar manner. Then, ostensibly while the polyester resin in both laminated parts is still wet (i.e., not fully cured because it is exposed to air), these two laminated parts while still in their molds are connected, and their two molds are clamped together. These molds are very strong and well-reinforced. Then into the open air space between the hull and the liner, an expanding foam is injected under pressure through a gate valve, and the foam expands to fills the space between hull and liner. By careful production techniques, the amount of foam is that will be controlled so the expansion of the foam is contained in order to create a higher density foam compared to foam expanding against only air pressure, and the Unibond hull is created.

Visit this page to see the process:

Boston Whaler Factory Tour
https://continuouswave.com/whaler/refer ... ctory.html

The result is that when a hole is made through the transom, the hole will expose some of the foam layer, and if water can enter that hole, it will be in contact with the foam. The extend that the water will be absorbed into the foam cellular structure should be limited. But the water can certainly travel in the wood, producing problems. Note that saltwater does not tend to cause rot in wood. To create rot in wood requires freshwater.

[jimh]

Q5: could [seawater] have leaked into the foam of the hull?

Yes, see my reply above to Q4.

Q6: should I worry about water intrusion past the transom and into the hull foam?

Yes. There is ALWAYS a proper concern for any water--seawater or freshwater or rainwater--to be allowed to enter the internal foam of the Unibond hull.

[jimh]

ASIDE:

Q7: what is the purpose of the many machine screw fasteners with large washers on the transom of your boat as seen in Figure 3?

[islavov]

Q7: what is the purpose of the many machine screw fasteners with large washers on the transom of your boat as seen in Figure 3?

The screw fasteners seen in Figure 3 are for the swim platform. I am sure that is from the factory. The screw fasteners are not through-bolted. The swim platform is solid.

[islavov]

Q8: is the bottom of the transom connected via a hole with the foam between outer skin and inner skin to where the fuel tank is located?

I drilled a test hole in the transom [on center line just a few inches above the hull bottom and is shown in FIgure 4 below]. About eight ounces of water leaked out of the test hole.

Fig. 4. The red dot shows the location of a test hole that was drilled. In case this illustrations is not clear, the hole was located on centerline at the transom a few inches above the hull bottom.

redDot.png (2.51 KiB) Viewed 163 times

Q9: can water enter the foam that is between the outer skin [the hull] and the inside skin [the liner] below the engine splash well?

I am trying to see if I have a even bigger problem. I have been monitoring a [cockpit deck] delamination [forward from] the console. The floor delamination is [farther forward than] the fuel tank. The delamination [is in an area of the hull] where [below the cockpit deck the structure of the hull] is just foam underneath [the laminated deck].

I may now be paranoid.

First, I will deal with the problems in the transom through-hull drains.

[islavov]

I bought two stainless steel through-hull fittings [from a vendor called GEMLUX to replace the OEM fittings] for the deck drain and the livewell drain on the Starboard side of the transom.

For the Port side cockpit drain I could not find a stainless steel replacement through hull fitting, and I used a push-in plastic fitting from PERKO similar to the OEM fitting.

[These will be installed] whenever I get to the [replacing the through-hull] fittings. I am a long way from [that step in the repair].

From what I can see, the wood needs to be removed from the transom. My hope was I could dry the wood in place. Now I feel the the transom bottom wood is rotted.

I will have local shops look at the boat and give me opinions and estimates [for repair of the rotted wood in the transom].

[islavov]

The result is that when a hole is made through the transom, the hole will expose some of the foam layer, and if water can enter that hole, it will be in contact with the foam. The extend that the water will be absorbed into the foam cellular structure should be limited. But the water can certainly travel in the wood, producing problems. Note that saltwater does not tend to cause rot in wood. To create rot in wood requires freshwater.

This does not seem like a smart design from Boston Whaler.

If I am following correctly, [the construction of a Boston Whaler Unibond hull] means transom water intrusion will expose the foam to water. From what I know, the foam will somewhat saturate with water.

Fig. 5. A section from a drawing from Boston Whaler showing construction of a Unibond hull for the 190 NANTUCKET. A red circle and a red line direct attention to the area of the hull near the transom.

BW_Nantucket190dwg.jpg (30.5 KiB) Viewed 153 times

Q10: how can I know if water has saturated the foam?

[jimh]

Q8: is the bottom of transom connected with a hole with the foam between outer skin and inner skin where bilge is and fuel tank up front?

The Unibond hull foam interior is one continuous open space that was filled with foam. There are no separate compartments of foam.

[jimh]

Q9: can...water enter the foam that is between the outer skin [the hull] and the inside skin [the liner] below the engine splash well?

Yes. The Unibond hull foam interior is one continuous open space that was filled with foam. There are no separate compartments of foam.

[jimh]

Q10: how can I know if water has saturated the foam?

Your question is a frequently asked question. An answer to your frequently asked question is given in the answers in the Frequently Asked Questions or FAQ section. Please read at

Q3: Is there water in a Unibond hull?
https://continuouswave.com/whaler/reference/FAQ/#Q3

[jimh]

This does not seem like a smart design from Boston Whaler.

Boston Whaler has been building their Unibond Hull construction boats this way since 1959. This construction method is used in all Boston Whaler hulls. Considering the enormous growth of the company in the last 65-years and their present line of boats built with this method which in some models cost over one-million dollars, I would say the method has been quite successful.

[jimh]

Perhaps I have not explained the construction of a Unibond hull in a sufficient manner. I will try again.

The Unibond hull is made of two parts: the hull and the liner. Think of these like a shoe box: there is the big box with an open top, and there is the lid for the box. This is exactly like the the hull and the liner, although the shapes are different. The Unibond hull is just like taking a shoe box and its lid, spraying an adhesive on the inside surfaces, the quickly putting the lid on the shoebox, holding the lid very strongly to the shoe box, making a very small hole in the lid, then shooting in an expanding foam through the hole. The foam expands and fills the empty space inside the shoebox. When the foam stops expanding and cures it is glued to the box and lid, and the three parts, box, lid, and foam are are continuously bonded to each other.

Also, you could attach some stuff to the shoebox or the lid with adhesives before you joined them and introduced the foam, so that stuff would be embedded into the final structure. That is like the wood in the transom of a Unibond hull. It is placed in the hull and attached to the laminate and bonded to the laminate by the polyester laminating resin used in laminating the hull.

Inside the hull there are no separations or compartments. It's all one big empty space filled with foam. There is some secret stuff included to make connect rigid connections between the hull and liner. These are referred to as "shear ties." To learn more, read the patent about the Unibond hull. It is described in the REFERENCE section article at

Original Patent
of the Boston Whaler Hull Construction
https://continuouswave.com/whaler/refer ... atent.html

Also, I hope you looked carefully at the factory tour article I mentioned in an earlier reply. A photograph shows the production stage when a hull and liner mold are clamped together.

I hope you now have a clear understanding of how a Boston Whaler Unibond hull is fabricated.

Also, from the earliest days, there has always been great concern for allowing any water--rain, dew, seawater, lake water--to be able to enter into the sealed and closed interior of the Unibond hull.

[jimh]

Q11: has the particular 2004 190 NANTUCKET boat been used in saltwater or freshwater?

Wood does not tend to rot in saltwater.

But, somewhat paradoxically, if the hull interior is holding saltwater, getting saltwater to evaporate and dry will be more difficult than if the foam is holding freshwater. It may be useful to rise some areas lightly with freshwater to see if that might promote better drying.

[islavov]

This does not seem like a smart design from Boston Whaler.

Boston Whaler has been building their Unibond Hull construction boats this way since 1959. This construction method is used in all Boston Whaler hulls. Considering the enormous growth of the company in the last 65-years and their present line of boats built with this method which in some models cost over one-million dollars, I would say the method has been quite successful.

yeah I know and I agree - this is why I got me a whaler.
I still want to say, things can always be improved by a real use-case examples, and logically, it would have been a good piece of mind to know that transom water intrusion cant compromise and affect the hull in front.
Maybe I am biased now having a wet transom :)

[islavov]

Perhaps I have not explained the construction of a Unibond hull in a sufficient manner. I will try again.

Thank you.

[jimh]

...things can always be improved by a real use-case examples, and logically, it would have been a good peace of mind to know that transom water intrusion can't compromise and affect the hull in front.

In the case of these plastic through-hull fittings that exit the transom below the water line, the apparently all-too-common failure of the plastic fittings is certainly a stain on the Boston Whaler reputation.

The real cause is not so much the plastic fittings themselves, but apparently the very strong connection of the fitting to an attached hose, and that attached hose somehow overtime experiencing a shrinkage, which then exerted a TENSION onto the fitting that exceeded the strength of the plastic material to resist, resulting in the plastic material yielding and cracking, resulting in water being able to enter into the passage drilled in the transom.

Whether such a future problem was reasonable to be foreseen by the engineers and designers of the c.2004 190 NANTUCKET is very difficult to know, because, as is often said, HINDSIGHT IS ALWAYS 20-20.

In 2004, Boston Whaler was about eight years into its ownership by Brunswick, and perhaps too many bad ideas and cost saving ideas had become standard practices in the construction of a Boston Whaler boat from the corporate owner's influence.