Motor mount screws

Bill Roosa · Dec 1, 2011

If you have access to the back side then just thru-bolt them with a backing plate. Toggle bolts will leak (bigger hole to pass the toggle) and probably work the fiberglass over time just like the screws did.
Fiberglass and point loads are not good friends. The toggles will dig into the glass just like a screw and chew it up as the motor makes the mount flex.

Crazy Dave Condon · Dec 1, 2011

I cannot recall if the backiing plate is wood or aluminum but suspect wood. The easiest way to fix this was to take the bracket off and drill for larger ss wood screws. You may have to drill the holes larger on the outboard motor bracket and caulk liberally.

If that is not the case, the nnext thing I did was to cut out for 4 iinch inspection port and then applied ss bolts, washers and nylon nuts. If the wood is wet, put boat in a dry place for 2 months and open the transom drain plug

crazy dave

txjim · Dec 1, 2011

dvpatton said:
Hello, everyone. I've had a heck of a time with the screws that affix the motor mount to the deck of my Hunter 170. I bought the boat new & the motor mount was affixed with metal screws screwed directly into the flat portion of the deck on the starboard side of the transom. The screws have stripped & the motor mount is no longer secured to the deck properly.

I've been thinking of replacing the original screws with 3/8 inch toggle bolts. That way, I figure that there would be mechanical force both above & below the deck to hold the motor mount secure.

Has anyone run into this or a similar issue? Any thought or ideas would be greatly appreciated.

Thank you!

DV, I've had to rebuild my motor mount due to water saturation. It's a piece of plywood embedded in the foam which makes up the structure of the deck and cannot be considered capable of supporting a great deal of weight or torque. If (and only if) you believe the plywood backer is intact and bonded to the foam then larger bolts should work. Verify the plywood is dry before you do anything, drill test cores if necessary! Toggle bolts will have problems as there is insufficient space between the cap and the hull for toggles to work for 2 (and maybe 3) of the 4 bolts.

You can have a serious problem if the plywood is no longer bonded to the foam (such as what would happen if the plywood delaminated) as the torque of the motor would transfer stress to the deck plastic shell and rip the shell. Motor hits the drink when this happens.

If the plywood is not sound then it can be successfully repaired. I'll be happy to post details if this is the route you take.

txjim · Dec 1, 2011

Crazy Dave Condon said:
I cannot recall if the backiing plate is wood or aluminum but suspect wood. The easiest way to fix this was to take the bracket off and drill for larger ss wood screws. You may have to drill the holes larger on the outboard motor bracket and caulk liberally.

If that is not the case, the nnext thing I did was to cut out for 4 iinch inspection port and then applied ss bolts, washers and nylon nuts. If the wood is wet, put boat in a dry place for 2 months and open the transom drain plug

crazy dave

The plywood used in my '99 was fully delaminated with individual layers warped. No amount of drying will fix that! Only answer is to replace the wood and I took that opportunity to bond the mount to the hull instead of relying on the deck foam alone. The mod uses the existing deck plastic so the boat looks like it did before the repair!

Crazy Dave Condon · Dec 2, 2011

txjim said:
The plywood used in my '99 was fully delaminated with individual layers warped. No amount of drying will fix that! Only answer is to replace the wood and I took that opportunity to bond the mount to the hull instead of relying on the deck foam alone. The mod uses the existing deck plastic so the boat looks like it did before the repair!

was the wood added underneath or topsides?

Crazy dave

txjim · Dec 2, 2011

The wood I added replaced the plywood in the deck 'bump' where the bracket mounts. I carefully cut the deck plastic arount the mount to remove the existing wood. As mentioned, the existing plywood was fully delaminated to I only had to clean the upper ply from the plastic before fitting it's replacement. The hull is close to the deck at this point so I made the replacement wood thicker and trimmed it to match the contour of the inner hull.

With appropriate trimming, I was able to epoxy the mount to the hull while still maintaining proper positioning with the deck. I integrated the new addition to the foam of the cap with 4 pound 2-part expanding foam. The plastic portion of the cut-out mount was glued to the wood and the seam between cut plastic and deck plastic glued using the documented methods. I had 2-part paint matched at an auto paint supply shop.

Final assembly relys a bit on proper timing as the foam expands but it's a very strong result.

The original Hunter method depends a bit too much on the strength of the structural foam which is why people have to think hard about heavy outboards.

Crazy Dave Condon · Dec 3, 2011

You hit it on the head when you said heavy outboards. I have always suggested the Honda 2hp which is ideal in all condiitons. Another issue was people using that as a hold on trying to get out of the water.

You are correct when the wood delaminated , it had to be replaced with wood.

a few notes. When painting the hunter plastic, you can use the krylon spray paint for plastics. I forgot which one but you can email customer service at Hunter and they can tell you. Other paints may not hold for long or can be very expensive.

Whenever doing a repair, always have the edges of the hole at 45% angles from the inside to the outside. Many reasons for that suggestion.

Keep me posted on how your repair holds up sir. Thank you for being detailed. It sounds to be a good repair.

crazy dave condon

esterhazyinoz · Jan 11, 2012

Crazy Dave,
As you have such comprehensive knowledge about the Hunter daysailers, would you recommend the Honda 2HP short or long shaft? Note, I only sail my H15 in our river but that can get some good sized waves in the larger, bay sized bodies of water there.

Crazy Dave Condon · Jan 12, 2012

On all daysailors the Honda 2 hp is a good fit even for the 15, 18, 170, 146, catalina 14.2 adn 16.5, precision 15 and other daysailors. It depends on the area to be sailed as the shaft length needed and of course how low the outboard motor bracket sits off the water on the back of the transom.

crazy dave condon