Leak Into Rear of 98 Mac X.

[mwalsh0]

Advice needed please. I am trying to source an irritating leak into the rear berth of my boat, a Mac x. When it rains I get a drip coming off the inside lining of the motor well, just at its lowest point. Unfortunately this drip falls on the mattress and over a period can be substantial. I have tried many things including re sealing around the seat area and engine area. I am hoping that some of you may have had a similar issue and might share some advice please?

[kmclemore]

Several areas can leak.

- port where cables to motor go thru the transom (and water can then travel down those cables until the low point).

- tube to the drain for the motor well can become dislodged at either end.

- caulk around the cockpit cubbies can, on rare occasions, be leaky.

- bolts into the cockpit sole holding the binicale (steering wheel station) can leak.

- water can run down the cables from the motor control n the side of the binacle, into the binacle, then into the boat.

Best bet is to get so someone to gently flow water from a hose over selected areas and watch carefully inside... start from the lowest possibility to the highest, in terms of elevation on the boat.

[dlandersson]

Sadly, a friend's X is having a simlar problem. I printed this out for him to use while troublshooting.

Several areas can leak.

- port where cables to motor go thru the transom (and water can then travel down those cables until the low point).

- tube to the drain for the motor well can become dislodged at either end.

- caulk around the cockpit cubbies can, on rare occasions, be leaky.

- bolts into the cockpit sole holding the binicale (steering wheel station) can leak.

- water can run down the cables from the motor control n the side of the binacle, into the binacle, then into the boat.

Best bet is to get so someone to gently flow water from a hose over selected areas and watch carefully inside... start from the lowest possibility to the highest, in terms of elevation on the boat.

[Dougiestyle]

Fuel lockers are possible leak (mine leaked both sides 98X) when they built these they caulked the lockers on the front lip, which many years later the caulking has dried out.

[OverEasy]

Hi Mwalsh0!

That’s an interesting problem that sounds familiar …..

What we did was look inside the pedestal at the cable feedthroughs where they penetrate the cockpit floor into the aft berth ceiling.
We had two penetrations. Both were factory. Both were not up to our expectations as far as workmanship or design.
Our solution was to redo these penetrations which required our removing the pedestal.
First we removed the cables from the smaller feedthrough which was for the throttle. It was the easier one to get started with.
After peeling away the goobered silicone ( NOTE: Never ever use silicone! It’s a waste of time. Use 3M 5200 instead)
We pulled out the PVC pipe and threw it away.
Cut a new length which would extend at least 6 inches above the cockpit floor and at least 2 inches below the aft berth ceiling.
We abraded the cockpit floor and aft berth ceiling two inches beyond the hole. Cleaned the surfaces with acetone. Wetted the interior surfaces of the hole with 5200. Wetted the surfaces of the replacement pipe with 5200. Inserted the replacement PVC pipe through and rotated it 360 degrees. Smoothed out neatly the excess 5200 around the top side. Then went and added a neat fillet around the penetration into the aft berth ceiling. Added a PVC coupler to the topside portion of the pipe to make a more finished appearance.

The larger aft feedthrough where the steering cable passes through was a bit more of a challenge as we didn’t want to disassemble the steering system. The existing PVC pipe was stopped at the top surface (internal) of aft berth ceiling as the hole wasn’t big enough to fit the Outer diameter of that pipe section. We removed all the goobered silicone from around the cockpit floor interface. Made a long narrow knife blade to cut away the crud that was partially restraining the pipe in place. Once free we slid it up the steering cable to get it out of the way. Then carefully opened up the hole in the aft berth ceiling with a dremel while protecting the steering cable. We cut a slot in a pipe coupler and slipped it over the cable above the existing pipe. Then we PVC cemented it to pipe and added PVC cement to the slot. We clamped the diameter of the coupling to get it to fit. This extended the length of the pipe about an inch. We repeated the process to add another short section of pipe (slotted) and coupler (slotted) to give a 6” improvement in height above the cockpit floor. Then following the same process as before abraded the surfaces two inches around the hole top and bottom, cleaned with acetone, wetted the hole interior with 5200, wetted the pipe with 5200, inserted & twisted 360 degrees after penetrating the aft berth ceiling. Made a nice neat topside and bottom side fillet with 5200.

We also took time to redo and seal with neoprene washers, fender washers and 5200 the pedestal mount boltings to the cockpit floor.

While involved and tedious it did significantly eliminate the water drips we were having at the aft berth engine bowl back lip that had been dripping. Our hypothesis was that water was getting in at the feedthroughs and traveling along the aft berth ceiling shell back to the interior space of the engine bowl area. There is actually a bit of a hollow space between the top surface shell and the interior shell.

After over a year of operations in fairly aggressive rain storms the leakage is about 95% reduced from what we had experienced previously. So there must still be another source of water penetrating. Our next step is to strip and reseal the interface on the cockpit side wall and the floor of the fuel cubbies which are the next potential culprits.

Best Regards,
Over Easy

[dlandersson]

As I understand it, 3M 5200 is fairly permanent, vs, 3M 4200 - which works well, but can be removed later if needed to reapply?

After peeling away the goobered silicone ( NOTE: Never ever use silicone! It’s a waste of time. Use 3M 5200 instead)

Best Regards,
Over Easy

[kmclemore]

As I understand it, 3M 5200 is fairly permanent, vs, 3M 4200 - which works well, but can be removed later if needed to reapply?

Correct.

[OverEasy]

Hi Diandersson!

Yes, Kmclemore is correct that 4200 tends to be “more” removable but I’ve found that for 99% of the applications that 5200 is the one and done “go-to” sealant. I find that both 4200 and 5200 are substantially better than any silicone goop out there.

Heck, I’ve even used less than an ounce of 5200 to fix the gutter end caps that the installers goobered up with half a caulking tube gun of “Premium Lifetime” gutter silicone. That stuff looking like a dog’s chew toy, smeared over everything, turned opaque and DIDN’T seal the gutter endcaps past the first summer.🫣.

To remove either 4200 or 5200 is relatively simple with mineral spirits and a roll of paper towels.
From my experience I really don’t see 4200 as being any more or less removable than 5200, nor would I really want it to be.
How many times am I really gonna be removing a feedthrough or deck fitting anyway?
If one does it right such things should last nearly forever.

Now there are other sealants out there and they do have thier application uses where they shine in their own right … like polybutylene window gasket putty for the Mac cabin windows. That’s a place where you do want a sealant that lasts nearly forever, can be re-compressed years down the line and when the windows inevitably UV craze and crack can be very easily removed without leaving any reside on the fiberglass to argue with unlike most silicone seal products that tend to oxidize and fail at the surface interfaces intermittently.

Best Regards
Over Easy

[dlandersson]

Thx, I'm a little jumpy about "permanent" fixes

To remove either 4200 or 5200 is relatively simple with mineral spirits and a roll of paper towels.

Best Regards
Over Easy

[OverEasy]

That’s the nice thing about 5200… it’s as permanent as you need it to be and still easily removable!