1985 Montauk 17: Splash Well has Access Plate

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ddqarch
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1985 Montauk 17: Splash Well has Access Plate

Postby ddqarch » Thu May 26, 2022 7:58 am

I recently purchased a 1985 Montauk 17. The engine splash well has a six-inch round screw-in access plate. Under the access plate is a void in the Boston Whaler Unibond hull. When I bought the boat, the void under the access plate was damp. Yesterday I opened the plate and there was standing water in there.

The standing water may have got in the void after a hard rain during which the sump pump didn't come on, and there was standing water above the access plate.

I'm not sure of the purpose of the void. The six-inch round screw-in access plate could have been installed for access to engine mounting bolts.

I am not sure if the access plate is original or if it was fitted later.

Any feedback would be helpful. I love this forum. Thanks.

[Moderator's note: I rewrote this post to use proper terminology for the elements of the boat mentioned.]

MarkCz
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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby MarkCz » Thu May 26, 2022 12:50 pm

I have a 1987 Montauk. There is no access plate in the splash well.

There is a rectangular teak cover in front of the splash well that covers the cockpit sump.

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Phil T
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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby Phil T » Thu May 26, 2022 1:11 pm

The original selling dealer mounted engine resting on the transom and used lag screws for the lower bolts. Typical installation. No problems.

Someone after that decided to through-bolt the lower bolts rather than use lag screws. To gain access, that person cut the splashwell and dug out the structural foam. That person installed inspection port so they would not have to do fiberglass repairs.

Water in this cavity is a really big problem.

Honestly, you need to get all the water out of that cavity, as best you can. Tilt the bow up, Use a shop vacuum. Use a space heater.

Seal the inspection port with marine sealant for this season.

This winter you need to remove the engine.
--Dry out cavity.
--Refoam the cavity
--Repair the fiberglass and gelcoat of the splashwell.
--Remount the engine with redrilled lower holes in the proper location so they enter at the bottom of the splashwell.
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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Thu May 26, 2022 1:13 pm

I have never seen an access plate in the engine splash well of a stock MONTAUK 17. If there is an access plate there, some prior owner probably added it.

If the lower engine mounting bolts are not visible, the engine mounting was not done properly.

Read the FAQ at

https://continuouswave.com/whaler/reference/FAQ/#Q8

The guy who cut into the splash well probably did not follow the recommendations in the FAQ.

ddqarch
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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby ddqarch » Thu May 26, 2022 5:39 pm

This is all very helpful information, thanks to you all. I will follow JimH's recommendations.

Q1: is there more information on how to re-foam inside the area beneath the splash well?

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Thu May 26, 2022 5:57 pm

The most important element in the repair of the unscrupulous modification of the original hull of your 1985 MONTAUK 17 boat, as PHIL T has already mentioned, is to get the boat out of the water, open the access plate, and let any moisture (or actual liquid water) evaporate. The foam and any other material exposed by the unscrupulous modification must be allowed to dry completely.

Getting water out of the the foam in a Unibond hull of a Boston Whaler boat is not a rapid process. Depending on the amount of water that has been allowed to get into the unusual void created in the foam by the unscrupulous modification, drying out that area could take a while.

The most important aspect of drying out the now-exposed interior of the Unibond hull is to not let any new water get in there.

Promoting drying with a flow of air over the foam is a good approach.

Regarding filling the void with foam, the problem will be to get a high-density foam into the void. In the construction of a Boston Whaler Unibond hull the foam expands against a closed mold, well, closed except for an intentional sprue holes and a few small vent paths. This creates a higher density foam than if the foam just expands and displaces air to the atmospheric pressure. But even lower-density foam is better than a big void in the Unibond hull.

While you are doing this, look into the engine mounting. We don't have any information from you about the engine mounting height as the boat is presently rigged. The anticipated engine mounting height would be at least one-hole-up and perhaps two-holes-up. If you do not understand how engine mounting height is being described, read this article:

ENGINE MOUNTING HEIGHT
https://continuouswave.com/forum/viewto ... ?f=7&t=739

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby ddqarch » Thu May 26, 2022 9:06 pm

Thanks JimH for more good information (and Phil T for the original recommendation). The engine is mounted one-hole up. When I bought the boat it had a 2005 Yamaha 115 engine mounted all the way down, and performance was terrible.

I am reasonably sure that the splash well was cut open and the foam was removed to access the lower engine mounting through-bolts when the Yamaha engine was installed.

When I re-powered the 1985 MONTAUK 17 with a Suzuki 90, I tried to have the engine mounting height raised to be two-holes up.

The dealer said he could not [mount the new Suzuki 90 engine at two-holes-up] because there would be no way to get to the lower engine mounting bolts. The dealer wanted to re-use the same mounting hole {that were used for the Yamaha 115 engine]. Due to the elongated lower hole in the bracket, he could use those existing holes in the transom, and raise the engine mounting height one holehigher from where it was, but not two-holes higher.

I wish I had known at the time that lag bolting would have been an option. The only good news here is that due to the void, I can see and feel that the wood in the transom is quite solid.

A high-density foam was recommended.

Q2: Is there a particular foam product to use?

Q3: Should the foam be closed-cell?

Hardware stores are filled with cans of spray foam these days.

Q4: Will hardware store foam work?

Q5: Is there a better foam than hardware store foam?

Thanks again for all the good information.

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Fri May 27, 2022 8:33 am

ddqarch wrote:Q1: is there more information on how to re-foam inside the area beneath the splash well?

Q2: Is there a particular foam product to use?

Q3: Should the foam be closed-cell?

Q4: Will hardware store foam work?

Q5: Is there a better foam than hardware store foam?


These five questions are all the same question in different forms.

I don't have any first-hand experience in using a particular brand of foam to fill a void in the Unibond hull of a Boston Whaler boat, so I cannot give you a recommendation to a specific product.

As far as I can tell, all foam begins as "closed-cell" foam. There are bubbles in the foam when it is liquid. As the foam cures, I presume the bubbles remain intact.

Again, not from first-hand experience, but I believe others have commented that some foams are advertised as having a particular density when they have cured. The higher the foam is rated in density, the better the foam will be for use as a replacement for the original structural foam in a Boston Whaler Unibond hull.

Whether you can find a suitable foam at your local hardware store is unknown to me.

There should be some articles in the archives about using new foam. You can try a search, starting at

SEARCHING CONTINUOUSWAVE CONTENT
https://continuouswave.com/whaler/search.html

Try searching on these terms "replace foam unibond hull". Here is that search as a URL

https://duckduckgo.com/?q=replace+foam+ ... com&ia=web

Read all the articles found by the search and see if any of them are helpful to you. If not, try other search terms. The archives of this forum, the old forum, and the REFERENCE section contain over 100,000 articles, so I am sure something in there might be useful for you.

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Fri May 27, 2022 9:05 am

ddqarch wrote:The dealer said he could not [mount the new Suzuki 90 engine at two-holes-up] because there would be no way to get to the lower engine mounting bolts. The dealer wanted to re-use the same mounting hole {that were used for the Yamaha 115 engine]. Due to the elongated lower hole in the bracket, he could use those existing holes in the transom, and raise the engine mounting height one-hole higher from where it was, but not two-holes higher.
I have had two cups of coffee this morning, and re-read your comments several times, but I still do not understand what was inhibiting "the dealer" from raising the Suzuki engine to be at a mounting height of two-holes-up from lowest possible position.

You seem to mix the actual mounting height desired ("two-holes-up" from lowest possible) with the amount that the new engine was to be raised from where a previous engine was mounted ("raised two-holes").

I understand that the new engine ("Suzuki 90") engine mounting bracket has individual holes for the upper mounting bolt positions and has a long slot for the lower engine mounting bolts. That is a common arrangement these days.

The only basis by which the lower mounting hole would limit the engine mounting height would occur only if the lower engine mounting hole were drilled in the transom at some absurdly low and wrong location, and if so, the hole would not be useful for any mounting.

So far, no information has been given about where the engine mounting holes are located on the transom. The FAQ explains in detail the proper position for locating the engine mounting holes in the transom at

Q9: What is the Standard Transom Hole Layout?
https://continuouswave.com/whaler/reference/FAQ/#Q9

Read the FAQ and compare the hole layout on the boat with the standard hole layout.

Assuming that the holes in the transom were made for the original engine (the "Yamaha 115") and if that engine were mounted in the lowest possible position, then the lower engine mounting bolt hole in the transom would be located 8-inches below the the top mounting hole. There is then nothing that would inhibit another engine from being mounted as high as three-holes-up (if the engine has four sets of holes) or four-holes-up (if the engine has five sets of holes, as is now common).

In the FAQ, the recommended transom hole location for working around the problem of the shallow engine splashwell on the classic Boston Whaler hulls is the drill the lower mounting holes in the transom at a reduced spacing of 7.25-inches instead of 8-inches. The only influence of this hole spacing is that the engine cannot be mounted lower than one-hole-up. There is no effect on how high the engine can be mounted by reducing the spacing of upper-to-lower holes in the transom. The lower hole could also be drilled at a space in 6.5-inches from the top hole. The only influence of that hole spacing is the engine must be mounted at least in the two-holes-up position or higher. These reduced lower hole spacings only affect how LOW the engine can be mounted, not how high it can be mounted.

Based on this, the comment from the dealer that he was constrained in the engine mounting height makes no sense.

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Phil T
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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby Phil T » Fri May 27, 2022 12:14 pm

The dealer said he could not [mount the new Suzuki 90 engine at two-holes-up] because there would be no way to get to the lower engine mounting bolts. The dealer wanted to re-use the same mounting hole.


Your dealer hired a MORON as a technician.

Off the top of my head there are three ways to install the engine properly.

The fact that dealers charge $1XX.00 an hour for morons just boils my chowder.

Please take a dozen photos showing the engine and the transom, from the back, from the side, the splashwell with your phone and send them to me (check your email).

I will upload them to this thread.
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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Fri May 27, 2022 1:16 pm

All engine mounting problems resolve to being caused by two elements:
  • where the holes for mounting are located on the engine, and
  • where the holes for mounting are located on the transom.
With regard to the first element, every engine made after c.1984 has used the BIA mounting hole layout. There is literally no variation in the location of the mounting holes on the engine mounting bracket between engines, with the exception that on some engines there are four sets of holes and on other engines there are five sets of holes. The use of five sets of holes is common now, but for many years engines only had four sets of hole.

Another slight other variation in engine mounting holes can be the use of a long slot for the lower holes instead of individual holes spaced at 0.75-inch on-center. This is actual quite useful. A slot instead of individual holes for the lower mounting bolt allows for more leeway in the exact spacing of the transom holes as drilled in the boat transom. If the transom were drilled by some hack, and the hole spacing for the lower mounting holes was not exactly 8-inches offset from the upper holes, there could be an interference fit for the bolt if the engine mounting plate uses individual holes. A slot gives more slop in the fit, in case the transom hole spacing is not accurate.

The bottom line is the engine mounting bracket of a particular engine--as long as the BIA mounting bracket design is being used--will never be a problem for adjusting engine mounting height.

Not important to this particular discussion, I note that some really big, really heavy, really fancy new outboard engines may no longer employ the BIA mounting hole location. But you can be sure any 90-HP or 115-HP engine made after c.1984 will have a BIA hole layout.

The second element in engine mount is where the holes were drilled in the boat transom. The position of these holes should conform to the BIA specifications, but there is no guarantee that when the holes were drilled that they are precisely where they should be. As I have already described and already pointed to a thorough explanation in the FAQ, these older small Boston Whaler boats have a shallow engine splash well, and you CANNOT use the BIA position for the lower engine mounting hole in the transom because the fastener will end up buried inside the Unibond hull--exactly what apparently happened when someone first installed the "Yamaha 115" engine.

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Fri May 27, 2022 1:26 pm

Phil T wrote:Your dealer hired a MORON as a technician.
I have a kinder and more gentle view of this situation: the dealer, like most dealers these days, probably does not do much selling of loose engines for re-powering old boats, and in this case particularly, the dealer probably has not tried to fit a new engine on an old Boston Whaler open skiff with a shallow engine splash well. The dealer and his technician were just not AWARE of the proper solution to this. They never heard of Boston Whaler service bulletin 84-10: advice on mounting engines in shallow splash wells.

Service bulletin came out in 1984 because that is when outboard engines began to use the BIA standard hole position on the engine mounting bracket. You see how nicely that fits in with this problem we are discussing.

The TECHNICIAN probably was not even born by 1984. The dealer was probably not a Boston Whaler authorized dealer in 1984 and is not now. Those circumstances do not make either the dealer or the technician a MORON. It just makes them unfamiliar with older Boston Whaler boats with shallow engine splash wells.

Dealers like to install engines with BIA mounting brackets on boats that have holes in the transom for BIA mounting brackets, and then they like to mount the engine at the lowest possible position because of some unknown reason, but probably just from habit and perhaps because they think that is the best position or they think that if they mount the engine higher there will be problems with cooling water or propeller ventilation--no one really knows why some dealers think this way, but many do.

If you have an older Boston Whaler small open skiff with a shallow engine splash well, and you buy a new loose engine from a dealer, you may have to teach the dealer how to mount it, and insist that the engine be mounted at the height you want the engine mounted, not at the height the dealer thinks is best, and be willing to sign-off on the mounting height in case you were wrong and the performance is not good.

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Fri May 27, 2022 1:28 pm

Phil T wrote:Please a dozen photos showing the engine and the transom, from the back, from the side, the splashwell with your phone and send them to me (check your email). I will upload them to this thread.

PHIL is asking for 12 pictures because he wants to be sure to get the one picture that will show the problem. There is never a need for 12-pictures to show how an engine is mounted; just one good one is all you need.

One good picture of the access plate in the engine splash well will be fine, too.

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby Phil T » Fri May 27, 2022 1:57 pm

I asked for 12 photographs because I am interested in seeing the condition of the transom, the drains, the green line, and the inside transom face and splashwell area.
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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Fri May 27, 2022 3:03 pm

Good deal—now the photographer knows what to illustrate when he takes photographs.

Another hint or two: hold the camera horizontally or in landscape format. Don’t include too much extraneous stuff like blue sky, the neighbor’s car and house, three acres of empty field, a dozen other boats in the background, or young children.

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby ddqarch » Wed Jun 01, 2022 8:25 am

All the comments you have provided have been very helpful, and I have had two phone conversations with Phil T that really clarified my path forward. I plan to undo some of the damage done to the boat before I got it. In Winter 2022-2023 I will:
  • raise the motor to two-holes down [--must mean two holes up]
  • remove the existing lower thru-bolts and put new ones above the splash well
  • plug and repair the holes from the existing lower bolts
  • fill the void with "4-lbs density" expanding foam, and
  • repair the hole put in for the access cover.



IMG_4939.jpeg
Fig. 1. The location of the circular deck access plate is shown.
IMG_4939.jpeg (99.93 KiB) Viewed 340 times


IMG_4938.jpeg
Fig. 2. Close up of the engine mounting bolts that can be access via the circular access plate.
IMG_4938.jpeg (139.99 KiB) Viewed 340 times

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Wed Jun 01, 2022 11:29 am

As seen in Figure 2 above, you should reverse the direction of the lower engine mounting bolts so the nuts are on the engine side of the transom. Putting the bolts on the engine side of the transom will make it much easier to remove the engine from the transom, as might be done when changing engine mounting height or changing to a new engine.

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Wed Jun 01, 2022 11:31 am

Figure 1 reveals the deck access plate to be in a much different position than expected. I would have never thought of putting the access plate there. It does have the advantage of not cutting a hole in the bottom of the engine splash well; that prevents water sitting in the engine splash well leaking into the void.

The person who fabricated that hole certainly removed a lot more foam than necessary to get to the mounting bolts.

As for repairing that large circular hole, you may want to consider just leaving the circular access plate in place. To repair the hole with laminate and gel coat resin will need very skillful work.

Repairing Hull Damage the Whaler Way
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https://continuouswave.com/whaler/refer ... epair.html

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Wed Jun 01, 2022 11:34 am

ddqarch wrote:raise the motor to two-holes down...
I think you mean you plan to raise the engine mounting height to be two-holes-up from lowest position. To better understand how to describe engine mounting height positions, please, please--I am repeating please because this the second request--read the article on engine mounting height at

ENGINE MOUNTING HEIGHT
https://continuouswave.com/forum/viewto ... ?f=7&t=739

That article is pinned at the top of the forum, but if you just click on the URL above, it is a hyperlink and will take you to the article.

Do not try to describe the engine mounting height in terms of the position of the hole on the engine mounting bracket where a bolt will go. Describe the engine mounting height in terms of its location as raised above the lowest possible position in units of "holes" or 0.75-inches. Don't describe the engine mounting height in relation to where the engine is now. Describe the engine mounting height in relation to the lowest possible position on the transom that the engine can be mounted.

Engine mounting height describe in this manner ASSUMES that the holes that were drilled in the transom of the boat are located in the correct position according to the BIA hole layout. To learn more about the BIA Hole Layout, read the article pinned at the top of the forum

Transom Mounting Hole Layout for Shallow Splash Well
https://continuouswave.com/forum/viewto ... f=7&t=5808

Correctly locating the engine mounting holes in the transom is the first step in getting the engine mounted properly.

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby jimh » Wed Jun 01, 2022 11:46 am

Have you measured the location of the existing holes in the transom to see if they conform to the BIA hole layout?

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby ddqarch » Wed Jun 08, 2022 8:45 am

Jim and Phil: the top bolt [holes] are [located] according to the BIA layout, about 1-7/8-inch down from top of transom

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Re: 1985 Montauk 17: Splash Well has Access Plate

Postby Phil T » Wed Jun 08, 2022 11:30 am

That is the BIA standard measurement. Good.
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