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Author Topic:   Raising Engine Mounted with Blind Holes
ewalsh posted 05-29-2004 07:21 PM ET (US)   Profile for ewalsh   Send Email to ewalsh  
Hi all,

The 115 Johnson on my 1990 Outrage 19 needs to be raised one or two holes. The problem is the lower bolts use the blind holes in the engine's mounting bracket.

I really don't want to drill new holes in the transom which would let me use the lower slots to accomidate the raised engine position.

Do I have any choice? Am I missing any tricks? If not, any tips on how to drill the new holes and fill the old?

Thank you, Ed

Joe Kriz posted 05-29-2004 10:46 PM ET (US)     Profile for Joe Kriz  Send Email to Joe Kriz     

You have 2 choices for raising your engine that I know of.

1. Purchase a set back bracket and install it using the exisiting holes in your transom. Then you can raise or lower your engine on the bracket itself.

2. Drill new holes in the transom for the lower slots and fill the old "blind" mounting holes.

Number 2 above should have been done from the dealer in the first place. They unfortunately improperly rigged that boat for future adjustment or engine replacement. I hate that but there is nothing else to do at this point.

jimh posted 05-30-2004 09:34 AM ET (US)     Profile for jimh  Send Email to jimh     
You should re-drill the holes in the transom so that they conform to the standard pattern recommended for all outboards. Usually there is a template provided with a new motor that shows the location of the holes. If your current upper holes are in the proper location, it may just be a matter of drilling new lower holes.

On older Boston Whaler boats it is often seen that the splash well is not sufficiently deep to permit the lower bolt holes of the standard pattern to exit on the inboard side above the bottom of the splash well. Historically, this has been the cause of several workarounds. One often seen is that used in your case, the engine was mounted using an alternative hole layout and a special blind hole in the engine mounting bracket. Another alternative seen is that the gelcoat and laminate of the lower splash well were removed, the hole was drilled in the standard position, and the splash well repaired (or, in some cases, a removable hatch was installed). On some smaller boats the lower engine mounting bolts were not drilled through and bolted, and instead lag screws were used to secure them. Given these alternatives, the blind hole technique seems like the preferred situation to be in at the present.

If the transom and splash well arrangement permits use of the standard layout, you can repair the old holes and re-drill new ones. To repair the old holes it is recommended you fill them with wooden plugs. Some have suggested dowels, and others, for whom carpentry is a vocation, an advocation, a hobby, or an obsession, have suggested that use of dowels be eschewed and instead a plug ought to be cut from similar plywood material so that the grain and compressive strength of the plug be better matched to the original. To me, someone for whom "lumber" is something you try to avoid hitting with your car when you see it ahead on the highway, it is hard to judge if this distinction between a dowel and a plug is crucial. I believe that the reason behind it is to prevent the transom from having a "hard spot" which might cause the laminate or gelcoat to crack when a compressive strain is placed on the area by the tightening of the engine mounting bolts.

Once the hole has been filled with dowel or plug, as you will, then the rest of the repair is easy, although one must choose between polyester resin and epoxy resin, and again, there are advocates for both. Finally, a layer of closely color matched gelcoat resin should be applied, and for this there is little dispute, although some like to mix their own and others send for Spectrum Color's color-matched material.

There you have it, engine raising made simple, or complex, as it were.

ewalsh posted 05-31-2004 08:45 AM ET (US)     Profile for ewalsh  Send Email to ewalsh     
Thanks all.

It appears that the blind holes do not line up vertically with the lower adjustment slots on my 1991 Johnson 115, so the drill will have to come out.

Regards, Ed

Plotman posted 06-01-2004 01:07 PM ET (US)     Profile for Plotman  Send Email to Plotman     
If it were my boat I would try to use a simple fixed jack plate like the following for $85 from west marine.

I would much prefer to drill new lower holes in aluminum to get the bracket to match the existing holes in the transom than mess about with drilling and filling the transom.


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