1985 MONTAUK 17: Preventing Water Overflowing Transom

[Teleni]

Give me advice for fabricating a device to prevent seawater from overflowing the transom of 1985 MONTAUK 17 and entering the cockpit.

I do a lot of angling in the Pacific Ocean seaward of the Golden Gate Bridge in San Francisco, and at times the conditions are [severe] out there.

[jimh]

Being stern-to to large ocean waves in an open 17-foot skiff is probably not the best situation. Perhaps a larger boat with a full transom, a cockpit whose deck level is above the waterline, and large scuppers to permit rapid draining would be better for those conditions.

Or, invest in a really good pump to very very rapidly evacuate any water that comes aboard, and have a large battery to handle the power consumption from that big pump.

[MarkCz]

I have a similar vintage Montauk 17 and on a few occasions wish I had some kind of spring loaded flap on each side of the motor to keep water from entering over the transom notch. I never got around to building the thing, but I wanted a sort of one-way-flap that if need be would open if I took on lots of water and gave the engine some throttle to get the bow up and drain some water out of the notched transom. I can not afford a larger boat, but I do try to pick my days with good weather to minimize what you described.

[Phil T]

Keep in mind the open(-ish) transom of the Montauk is a good thing. When you take 40-50 gallons over the stern or bow, having a lot of that water go out the back when you mash the throttle is a good thing.

If you raise the transom wall on both side of the engine, install swing-out doors that are large.

I disliked the closed transom of my Outrage 17 I for rough seas since it has a small open transom and evacuating large water is slow and every second counts. I would run with a 2-gallon pail available to help evacuate the water when it got above my ankles at the console.

Adding a large bilge pump on the deck forward of the sump with a large smooth discharge hose will go a long way.
https://www.wholesalemarine.com/albin-pump-bilge-pump-heavy-duty-2250-gph-12v/

I was going to install something like that on my Outrage 17 but I moved off the ocean.

[jimh]

The Boston Whaler boat most appropriate to use for offshore angling is probably the OUTRAGE 25. That boat has a very wide and completely open transom. The engine splash well is also full-width. The splash well can capture water coming over the transom and immediately drain it out to the sea via the splash well drains, but the rate of draining is not particularly fast as the diameter of the splash well drain holes only about one-inch and there are only two or three drains.

If a wave comes aboard from astern that is high enough to continue right over the engine splash well and into the cockpit, the best action to take is to immediately increase boat speed and adjust trim to get the bow to rise. This will encourage the water to go out of the boat the same way it came into the boat: over the transom.

Approaching a solution to this problem by reducing the open area of the transom as a prevention is a bit risky. Any intentionally added obstruction to water coming aboard will also obstruct water from going out and over the transom. The suggestion that any such obstruction employ a flapper-valve is appropriate. There should be hinges that open in only one direction, and those hinges probably should not have spring tension on them trying to hold them closed.

A further consideration is the strength of any such structure you plan to fabricate. The force of a wave hitting the barrier from seaward or the force of a large volume of water rushing aft and hitting the barrier and trying to open the flappers could both be quite large. The device would need to be firmly attached to the hull so that it cannot be torn off by the forces of the water in either direction.

[MarkCz]

You may want to search for the words: back trolling transom splash guards. Walleye fisherman often backtroll to go slow and have fabricated some devices to minimize water ingress while still allowing water egress.

[Denny 47]

The rigs that walleye anglers have on the stern of their boats [that are intended to prevent waves coming over the transom] are called Wave Walkers. A Google search [using the search term “wave walker”] will find [links that may] reveal how they are constructed.

On a 1989 MONTAUK 17 I constructed a two-part “wave walker” using KING StarBoard and rubber that provided space for the outboard engine and still allowed it to pivot. [My homemade “wave walker”] worked well on the Columbia River [to prevent] waves of good size [from splashing over the transom of the MONTAUK 17].

[MarkCz]

[A commercial product website about "custom made splash guards" to prevent water overflowing the transom is:]

https://wavewackers.com/