2013 MONTAUK 150: Water in Unibond Hull from Anchor Locker Drain

[carkit]

Q1: should I be concerned that a MARELON through hull drain located in the anchor locker of my recently purchased 2013 150 MONTAUK was loose, and that upon removing it I found the surrounding foam to be wet?

Fig. 1. MARELON fitting on hull exterior

marelonFitting.jpeg (38.97 KiB) Viewed 494 times

Fig. 2. View looking into empty drain hole after fitting removal.

exposedFoamDrainHole.jpeg (61.41 KiB) Viewed 522 times

BACK STORY
I recently purchased [a 2013 150 MONTAUK] that is in great shape with 210 hours on the Mercury 60-HP BigFoot engine when purchased. The interior and exterior [are] in near perfect condition. After I got the boat home I found a few problems. FIrst I will tell you about two problems I have already fixed:

• The engine skeg has a "shield" on it that coverd two missing chunks of material about the size of a 50-cent coin. I have a guy to weld a new piece to repair that.
  
• The engine gear case held some water. I found this after draining the gear oil. I did a pressure test to see if [the source of the water ingress] was the propeller shaft seals; it was not. I dropped the gear case and tested the shift seal; [that was not the source of the water ingress] either. I removed the water pump, and there I found [the source of the water ingress into the gear case was the] on the crankshaft [unclear, perhaps means drive shaft] seals. I replaced the crankshaft [perhaps means drive shaft] seals and did another pressure test. Now there are no leaks. I replaced the water pump impeller and all the pump seals.

Now I will get back to the actual purpose of this post.

The first two times I went out in the 2013 150 MONTAUK I noted that the hull listed to starboard no matter where I stood. The boat did not seem to be sitting low in the water, but I did not have another to compare to.

I checked the plastic through-hull drain in the anchor locker. I found it to be very loose and was not sealed at all. I removed it very easily and found that the foam was wet to the touch. I hope there is not much water in the hull. I have had the boat in the water maybe about five hours total but don't know how much it was used before me while the thru hull was leaking.

PLANS FOR REPAIR OF WATER IN HULL

I have the boat in a garage on a trailer with the bow raised as high as I could get it and the bow is higher than the stern. I plan on putting a block under the jack to get the even bow higher. I was considering drilling a couple of small holes low in the transom to see if water comes out. Later after that I plan on filling the thru hull drain hole, which is 1.625-diameter, with thickened epoxy then drilling out and installing a 3/4-inch brass or bronze threaded through-hull fitting with a nut.

ASIDE ON BOAT PERFORMANCE AT FULL THROTTLE
The 2013 150 MONTAUK gets on a plane very quickly and runs at 30-MPH at full=throttle on the Mercury 60-HP BigFoot engine

[NorthShoreWhaler]

The anchor locker drain should be well above the waterline.

Q3: was the boat stored in the water before you bought it?

I wouldn’t start drilling holes in the transom looking for water.

The starboard list might be caused by battery and fuel tank placement. My 150 Super Sport always lists a little starboard because the two 6-gallon fuel tanks are on that side. The 15-foot hulls are very weight sensitive.

Try to post a picture of the boat in the water if you can.

[carkit]

Fig. 3. Static trim of 2013 150 MONTAUK showing location of the anchor locker drain outlet relative to the waterline at the bow.

boatStaticTrimBowView.jpeg (39.89 KiB) Viewed 520 times

As seen in Figure 3 above, the outlet of the anchor locker drain at static trim is above the waterline.

[Regarding the list to starboard,] the 20-gallon [on-deck] fuel tank is located on centerline. One of two batteries, a heavy trolling motor battery, is located to port side. On the transom a Power-Pole (weighing about 35-lbs without its hydraulic actuators) is mounted off-center [but not indicated on which side] and that may be throwing off the lateral trim balance.

NOT DRILLING HOLES
I have already decided not to drill any holes. I am just going to remove and check the hull drain that is in the sump pump well. I will replace both the anchor locker drain and the sump area drain with new two-piece MARELON replacement fittings.

[NorthShoreWhaler]

i would guess that you’re correct in the power pole being the source of the list. Boat doesn’t appear to be floating too low based on that photo.

[carkit]

Q4: what type of through-hull drain should I install to replace the original drains?


ASIDE: The photo in Figure 3 was taken on the first trip that we made in this boat on June 28, 2026. We made a few more trips after that. I need to take a new photograph after I replace the throught-hull fitting, and then compare [the position of drain outlet at the bow] to this one to see if there is any difference [in the boat static trim].

[jimh]

Q1: should I be concerned that a MARELON through hull drain located in the anchor locker of my recently purchased 2013 150 MONTAUK was loose, and that upon removing it I found the surrounding foam to be wet?

Yes. Any path that allows water to perpetually be in contact with the interior foam is a concern. If you can find an exact replacement fitting, when you install it be sure to create a better seal to the hull to prevent water ingress.

Boston Whaler demonstrates the procedure to replace through-hull fittings on modern boats made of plastic (not brass) on their youTube channel at:

Replacing a Thru-Hull
https://www.youtube.com/watch?v=Zby76eoKO-I

In that installation of a new drain, the interior wall of the drain tube passage appears to have a generous coating of sealant applied to it.

If you perform a similar procedure, be sure to NOT use a super strong adhesive sealant, just use a normal sealant with relatively little structural adhesive quality. If you use a super adhesive you will never be able to get that drain tube out of the hull if replacement is needed again.