problem defined:
Where 3/4” S.S. Rod meets the chain plate anchor, rod snapped (Tensile stress ) from the load of the standing rigging on about 25 knots of wind. Upon examination, it was clear that the s.s. Rod had corroded through more than 50% of the full diameter. (see photos)
1. My solution after discussions with the marine surveyor sent by Geico Boat Insurance was to fabricate out of 304 stainless steel a new chain plate anchor externally mounted above the existing, rusted chain plate anchor shown in the photo and attach the new external chain plate anchor to the existing chain plate anchor by boring eight holes into the existing, rusted anchor and two holes into the hull insert stringer that line up exactly with the holes in the new chain plate anchor. Although the existing chain plate anchor looks worthless on the surface, it was incredible difficult to drill 3/4” inch holes through it. Only one hole didn't have any “bite” due to too much rust.
2. I resolved the question of how to attach the new anchor to the old anchor by using “chemical” bolts. In a nutshell,
a) drill the 3/4” holes that line up exactly with the center of the 3/8th inch holes in the new chain plate anchor (critical)
b) insert “Red Head” umbrella anchors (HBU-38) through all the 3/4” holes (the anchors need a larger hole than the new chain plate external anchor holes, 3/8th inch)
c) cut 6” to 8” lengths of 3/8” inch stainless steel threaded rod (a little longer than needed is better than too short...then cut off extra length when complete. )
d) Get all your threaded rods ready to insert into the RED HEAD umbrella anchors now inserted in all the holes drilled in the old anchor. Also get the newly fabricated chain plate anchor ready to put over the RED HEAD anchors.
e) Timing, speed and accuracy is critical in this next step. Flood all the inserted RED HEAD anchors with RED HEAD A7 Epoxy. The key is the get enough epoxy into the umbrella anchor to expand the umbrella and form an umbrella shaped plug that will not pull through the hole when under stress. Each time a umbrella anchor is filled with A7, insert a piece of threaded rod by screwing it into the umbrella anchor counter-clockwise. Do this quickly then move on quickly. Make sure your have at least two tubes of A7 on-hand and ready to apply. As soon as all the epoxy is in and all rods are inserted, it is critical that the new chain plate anchor is inserted over all the new s.s. Threaded rod that have just been epoxied. This is why it is critical to make sure all of the centers of your 3/8” holes in the new chain plate anchor match up with the centers of all the ¾' holes drilled in the old chain plate anchor. Get the new s.s. chain plate anchor over those newly inserted threaded rods quickly...don't be timid.
3. Now that the new chain plate anchor is mounted over all the s.s. Threaded rods that have just been inserted into the RED HEAD A7 epoxy, make sure the new chain plate is a flush as possible with the old surface and now let the epoxy cure before putting on the s.s. Washers and nuts and beginning to tighten them down.
RED HEAD A7 epoxy (around $20.00 per tube)
RED HEAD umbrella anchor ($5.00 each if you can find them per piece...I have 12 of these left if you need some)
Important: Be sure to check and re-check all my measurements as sometime things had to change at a moments notice and were not documented here.
Note: The old 3/4” s.s. Rod was cleaned up at the end and two s.s. Nuts were used to join the deck upper chain plate to the new chain plate anchor. The old 3/4” rod is not attached to the old chain plate anchor directly.
Note: At the far right side (picture) of the new chain plate anchor, a triangle shaped slit was cut into the s.s. To allow the bolt and nut from the old chain plate anchor the protrudes from the existing fiberglass to slide into the new chailplate anchor where new s.s. Washers and nuts are used as an additional fastening point...connecting the old anchor to the new anchor.
Note: the far left side of the new anchor has two threaded bolts that are epoxied into the boat's hull insert stringer for additional support.
Note: After epoxy has cured (give it a full day even though A7 only needs a couple of hours), slowly start tightening down each nut beginning with your fingers. Get them all on, then go to each one and give each one the same amount of turns until the entire anchor unit is snug against the boat's fiberglass.
DO NOT OVER-TIGHTEN.
Note: This fix has been tested for over one year in thirty-five (35) knots of wind on Lake Lanier in the state of Georgia.
Site will not allow me to upload any more photos of my prototype....
Deck chain plate which is welded to the 3/4” s.s. Rod that snapped.
Underside of the deck chain plate where the 3/4” s.s. Rod is welded.
Maybe only 1/3rd of the s.s. Is good prior to break. I believe the rust on the hull embedded factory regular steel chain plate anchor caused a “dissimilar metals issue” with the stainless steel rod even though steel and stainless steel are not considered dissimilar metals. Geico Issurance company didn't pay one penny to help with this repair.
Where 3/4” S.S. Rod meets the chain plate anchor, rod snapped (Tensile stress ) from the load of the standing rigging on about 25 knots of wind. Upon examination, it was clear that the s.s. Rod had corroded through more than 50% of the full diameter. (see photos)
1. My solution after discussions with the marine surveyor sent by Geico Boat Insurance was to fabricate out of 304 stainless steel a new chain plate anchor externally mounted above the existing, rusted chain plate anchor shown in the photo and attach the new external chain plate anchor to the existing chain plate anchor by boring eight holes into the existing, rusted anchor and two holes into the hull insert stringer that line up exactly with the holes in the new chain plate anchor. Although the existing chain plate anchor looks worthless on the surface, it was incredible difficult to drill 3/4” inch holes through it. Only one hole didn't have any “bite” due to too much rust.
2. I resolved the question of how to attach the new anchor to the old anchor by using “chemical” bolts. In a nutshell,
a) drill the 3/4” holes that line up exactly with the center of the 3/8th inch holes in the new chain plate anchor (critical)
b) insert “Red Head” umbrella anchors (HBU-38) through all the 3/4” holes (the anchors need a larger hole than the new chain plate external anchor holes, 3/8th inch)
c) cut 6” to 8” lengths of 3/8” inch stainless steel threaded rod (a little longer than needed is better than too short...then cut off extra length when complete. )
d) Get all your threaded rods ready to insert into the RED HEAD umbrella anchors now inserted in all the holes drilled in the old anchor. Also get the newly fabricated chain plate anchor ready to put over the RED HEAD anchors.
e) Timing, speed and accuracy is critical in this next step. Flood all the inserted RED HEAD anchors with RED HEAD A7 Epoxy. The key is the get enough epoxy into the umbrella anchor to expand the umbrella and form an umbrella shaped plug that will not pull through the hole when under stress. Each time a umbrella anchor is filled with A7, insert a piece of threaded rod by screwing it into the umbrella anchor counter-clockwise. Do this quickly then move on quickly. Make sure your have at least two tubes of A7 on-hand and ready to apply. As soon as all the epoxy is in and all rods are inserted, it is critical that the new chain plate anchor is inserted over all the new s.s. Threaded rod that have just been epoxied. This is why it is critical to make sure all of the centers of your 3/8” holes in the new chain plate anchor match up with the centers of all the ¾' holes drilled in the old chain plate anchor. Get the new s.s. chain plate anchor over those newly inserted threaded rods quickly...don't be timid.
3. Now that the new chain plate anchor is mounted over all the s.s. Threaded rods that have just been inserted into the RED HEAD A7 epoxy, make sure the new chain plate is a flush as possible with the old surface and now let the epoxy cure before putting on the s.s. Washers and nuts and beginning to tighten them down.
RED HEAD A7 epoxy (around $20.00 per tube)
RED HEAD umbrella anchor ($5.00 each if you can find them per piece...I have 12 of these left if you need some)
Important: Be sure to check and re-check all my measurements as sometime things had to change at a moments notice and were not documented here.
Note: The old 3/4” s.s. Rod was cleaned up at the end and two s.s. Nuts were used to join the deck upper chain plate to the new chain plate anchor. The old 3/4” rod is not attached to the old chain plate anchor directly.
Note: At the far right side (picture) of the new chain plate anchor, a triangle shaped slit was cut into the s.s. To allow the bolt and nut from the old chain plate anchor the protrudes from the existing fiberglass to slide into the new chailplate anchor where new s.s. Washers and nuts are used as an additional fastening point...connecting the old anchor to the new anchor.
Note: the far left side of the new anchor has two threaded bolts that are epoxied into the boat's hull insert stringer for additional support.
Note: After epoxy has cured (give it a full day even though A7 only needs a couple of hours), slowly start tightening down each nut beginning with your fingers. Get them all on, then go to each one and give each one the same amount of turns until the entire anchor unit is snug against the boat's fiberglass.
DO NOT OVER-TIGHTEN.
Note: This fix has been tested for over one year in thirty-five (35) knots of wind on Lake Lanier in the state of Georgia.
Site will not allow me to upload any more photos of my prototype....
Deck chain plate which is welded to the 3/4” s.s. Rod that snapped.
Underside of the deck chain plate where the 3/4” s.s. Rod is welded.
Maybe only 1/3rd of the s.s. Is good prior to break. I believe the rust on the hull embedded factory regular steel chain plate anchor caused a “dissimilar metals issue” with the stainless steel rod even though steel and stainless steel are not considered dissimilar metals. Geico Issurance company didn't pay one penny to help with this repair.
