1996 Montauk 17 Hatch Hinge Repair

[MattFL]

[Here is the SHORT VERSION of this thread:]

The molded hatch cover on a 1996 MONTAUK 17 became detached from its hinge. The existing fasteners were removed. A new BARREL NUT was ordered and installed.

[For long version with beautiful illustrations, read on.]

Q1: on 1996 Montauk 17 anchor locker [illustrated in Figure 1], how is the hinge fastened to the [anchor locker hatch]?

Q2: on a 1996 Montauk 17 anchor locker [illustrated in Figure 1], how is the hinge fastened to the hull?

Fig. 1. The molded anchor locker hatch on a MONTAUK 17 which is the subject of this discussion.

anchorLockerMONTAUK17.jpg (21.9 KiB) Viewed 2568 times

Fig. 2. Close-up of cracked gel coat surrounding screw fasteners on hull.

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Fig. 3. Close-up of the screw fasteners on the hinge.

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Fig. 4. Close-up of fasteners on underside of hinge at hatch.

bottom_hinge.jpeg (43.25 KiB) Viewed 3055 times

The screw fasteners heads seen in Figure 4 are not connected to the screw fasteners from the top.

On my 1996 MONTAUK 17, on the [molded] anchor locker [hatch], one of the two hinges has broken loose [from its connection to the hatch]. The screws [holding the hinge in place] won't come out of the [molded anchor locker hatch]. The hinge is [loosely] attached; [the attachment of the hinge to the hull is] still tight.

I believe someone must have tried to close the hatch with a rope or something in the way, and the hinge fasteners were the weak point.

The surface of the [anchor locker hatch] under the hinge has split open. The screw threads look like machine screws. The screws come out three or four turns, but then just spin loosely and won't come out all the way, even when pulling them with pliers.

I'm guessing there must be a nut on the other side of some sort that has broken free of whatever was holding it.

Most of the visible area is still intact. I would like to figure out how [the molded anchor locker and the hull are] constructed to give me a better idea how to approach [removal of the broken fasteners] without causing too much unnecessary cosmetic damage.

[MarkCz]

You mention the screws on the bottom are not connected to the screws on the top which I find hard to believe as the location and spacing seem identical to to the screw location on the other side. What happens when you try to loosen the screws that are on the underside of the hatch? Just looking at the topside and bottom side it appears that a pair of sex nuts are used on the bottom and machine screws on the top side. The threads might have become galled and you may have to cut off the screws but it looks like you have enough room for a metal cutting blade to get in there. Oscillating tool with a quality metal blade would be my tool of choice to cut through the bolts. Let us know how the repair goes.

[jimh]

Barrel Nuts are often used to fasten hinges to molded fiberglass hatches.

See the REFERENCE article at

https://continuouswave.com/whaler/refer ... barrelNuts

[MattFL]

Your thought [perhaps directed to the comment by MakrCZ] was my initial thought, too, but the top screws are rattling around while the bottom screws were tight when I tried to move them.

I'll put more torque or maybe the impact driver on the bottom screws and see what happens.

Logically I can't think of any other way they would have done it, especially given the orientation of the top and bottom screws to each other. They must have broken inside somewhere, leaving part of the female side stuck on the male side, keeping the top bolts from falling out.

Q3: do I [apply] oil to [the screw threads of the screws that seem to be stuck] to prevent galling, in the off chance something might still unscrew?

Q4: would applying oil to the stuck screw fasteners make any future glass work a nightmare?

Q5: should I just break off the stuck screws?

Note that after 27 years of warm saltwater use in south Florida, there's not a spot of corrosion anywhere. Boston Whaler used some quality hardware on these boats.

[jimh]

It seems very likely that barrel nuts were used to hold the hinge on the hatch side.

As for the screw fasteners holding the hinge into the hull laminate, if they are definitely machine screws, they are probably threaded into a material called whale board that can be tapped to hold a machine screw. Work carefully with those fasteners. If you damage the embedded whale board threads, further use of them will be difficult.

Also, that long crack running across the anchor locker hatch seen in Figure 1 is unusual. It may be a result of the same forces applied to the hatch that broke the hinge screws.

[MarkCz]

I would not use an impact driver with stainless steel. I did that and severely galled some screws to the point where they were impossible to remove. I learned from that mistake.

[MattFL]

Update: [the fasteners used on the hinge] are indeed barrel nuts.

Fig. 5. Broken fastener hardware.

brokenBolts.JPG (12.13 KiB) Viewed 2571 times

Fig. 6. Removed bolts.

bolts_out.JPG (83.36 KiB) Viewed 2570 times

Fig. 7. A cracked lid.

crackedLid.jpg (33.33 KiB) Viewed 2570 times

Although these barrel nuts looked very nice on the outside, they were clearly corroded on the inside. The bottoms were held snug by corrosion, a good twist and the came free. I used an old drill bit as a drift and the top parts came right out with some very light tapping.

The associated screw fastener is good stainless steel and it has no corrosion.

The metal of the female side is copper colored--I wonder if it was actually copper. While [the corrosion is\ frustrating, to be angry [about the corrosion] after about 27 years of year-round use in saltwater would be difficult.

Where can an exact OEM replacement [presumably for the barrel nuts] be?

The cracks in the lid happened when the bolts broke. I'm trying not to cry too much about that. I'm thinking of applying a metal plate to the backside for strength when I put [the hinge and the hatch] back together.

[MarkCz]

Apex fasteners makes a line of high quality 316 stainless steel sex nuts or barrel nuts in many different lengths and thread sizes. 316 would hold up better than 304 stainless with respect to corrosion.

If you add a backing plate make sure the added thickness of the barrel nuts plus backing plate on the back side of the hatch will not make contact with the fiberglass lip that is usually under the hatch.

I don't know if Apex sells small quantities but I am sure you can find some online retailer that will sell small quantities.

I have bought 304 stainless hardware before and it will rust over time if exposed to saltwater and not thoroughly rinsed off.

Thanks for the follow up on how the repair was going.

[MattFL]

Thank you for the tips on the stainless.

The OEM screws are 10-24 thread.

The local Ace Hardware had some "steel" barrel [nuts] that matched that might work for the short term, but they are sure to rust very quickly.

I will look for some 316 stainless [fasteners] while these are in place temporarily.

[jimh]

I don't see anything in Figures 5, 6, and 7 that looks like a Barrel Nut.

A source for Barrel Nuts was given previously: BECKSON. See my earlier reply.

I am sure that Boston Whaler did not get their barrel nuts from their local Ace Hardware store.

The cracked area should be repaired with epoxy resin.

[MattFL]

The hatch is fixed. [The fastener that holds the hinge to the molded hatch top] was for-sure a barrel [nut] . The dimension of the barrel [nut] was 3/8-inch long with 10-24 threads. A replacement was ordered from Hamilton Marine, their part BEC-BB187S01 and installed.

Fig. 8. The actual package from a vendor from whom BARREL NUTS were ordered. Note on the package the vendors calls these products BARREL NUTS. The vendor does not call them BARREL SCREWS; please take note of this when describing these products in the narrative of this discussion.

package_.jpg (19.66 KiB) Viewed 2595 times

Fig. 9. Three fasteners in various stages of wear. On the left is an old barrel nut. In the center is a new barrel nut. On the right is an old oval head machine screw.

threeFasteners_.jpg (6.38 KiB) Viewed 2595 times

[Phil T]

These fasteners are also referred to as:

sex bolts
binding barrels and screws

Added vendors of them include:

McMaster- Carr https://www.mcmaster.com/products/sex-bolts/
Bolt Depot.com https://www.boltdepot.com/Browse.aspx?Units=US&Category=Sex_bolts_%26_Mating_screws&Subcategory=Sex_bolts&F_Material=Stainless_steel&F_Grade=18--8

[MattFL]

Looking at the pictures, I wonder if the original [barrel nut] was aluminum.

[jimh]

This thread is a record setting. It has set the record for the number of photographs (nine) needed to illustrate that the fastener used by Boston Whaler to secure hinges to a molded hatch cover was a barrel nut.

The REFERENCE article on RECOMMENDED VENDORS AND SOURCES at

https://continuouswave.com/whaler/reference/OEM.html

has an entry about BARREL NUTS:

https://continuouswave.com/whaler/refer ... barrelNuts

That entry consists of three sentences, and I think it provides the same information, that is, that the Boston Whaler used Barrel nuts to attached hatch hinges.

Regarding speculation that some component used to fasten the hinge on the 1996 MONTAUK 17 boat under discussion might have been made of aluminum: I doubt that Boston Whaler used aluminum hardware. Maybe a previous owner got an aluminum barrel nut or an inferior steel barrel nut from Ace Hardware. Maybe the OP can send you the old barrel nut for metallurgical testing. Contact the OP to follow up on your speculation.

Figures 5, 6, 7 appear to show a badly corroded barrel nut in which the threaded portion of a screw fastener has corroded in place and broken off in the barrel nut flush with the end of the barrel nut.

A big, warm, grateful thank you to all participants for their many replies to help the OP understand that the fastener was a barrell nut and to inform the OP where he could purchase barrel nuts. The OP appears to have found another source on this own and has bought barrel nuts.

[Thread now closed as we seem to have exhausted this very well illustrated topic of corroded marine hardware and its replacement with new hardware.]