Deck Repair: Six Questions

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
dyoung16611
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Deck Repair: Six Questions

Postby dyoung16611 » Mon May 24, 2021 5:32 pm

I learned about the “hammer tap” method for identifying soft spots on the deck of my 1983 Striper 15. I thought that before I go to the expense of a complete AWLGRIP [paint] job and redesign of the interior, I ought to make sure the deck was sound. Regrettably, I found an area about one- square-foot immediately aft of the area where the bow pedestal seat post contacted the non skid deck.

Using a Dremel tool, I cut through the 1/2-inch plywood under the non-skid gel coat and removed the deck section back to where the wood was sound.

deck1a.jpg
Fig. 1. Portion of foredeck cut out and removed.
deck1a.jpg (30.79 KiB) Viewed 4902 times


deck2a.jpg
Fig. 2. Removed section of deck.
deck2a.jpg (41.85 KiB) Viewed 4902 times


The repair advice from Boston Whaler does not address how to securely bond the replacement marine plywood to the underlying foam or to the original plywood along the aft edge of the new wood. Give me advice on making a repair of this type

Q1: Should I fill the minor foam divots lost when removing the old wood with an epoxy mash as described in the repair instructions?

Q2: Is replacement of the minor foam divots necessary?

Q3: Does the new wood need to be wetted where it meets the foam?

Q4: Would a proper repair involve feathering the surrounding skin back and laying 2 to 3-inch strips of cloth around the edges, overlapping the edges of the new wood and the surrounding gel coat?

Q5: Are there better ideas to properly bind the new wood to the surrounding areas?

While my cut runs along the smooth channel outside of the non-skid surface along the forward edge and the sides, it runs straight through the non-skid pattern along the aft edge

Q6: Is there any way to preserve the non-skid pattern and bond the aft edge of the wood without grinding the skin down and laying glass along that edge amd still have an acceptable bond?

I will appreciate anyone’s thoughts.
1983 15' Striper

Vance's Revenge
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Re: Deck Repair; Q7 and Q8

Postby Vance's Revenge » Fri May 28, 2021 4:12 pm

That is a pretty serious cut you made there--but it can be fixed.

Q7: Is it possible this is an original void in the hull?

Q8: Was the foam stuck to the underside of your cutout?

I haven't personally done this [type of repair to a deck] but have seen it in recorded presentations

Your illustrations do not show the size or depth of the voids in the foam very well.

To fix [voids in the foam] I have seen the voids filled with a can-version of marine foam bought at West Marine and trimmed down to level after it expands.

I absolutely would re-laminate your cut-out to the foam, but be careful about thick layers of epoxy resin setting up at one time.

On the website youTube there are presentations showing use of a mold pattern taken from the existing non-skid to mold the new gel coat to match the existing non-skid--and they looked like a lot of work.

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Don McIntyre - MI
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Re: Deck repair questions

Postby Don McIntyre - MI » Fri May 28, 2021 4:46 pm

The tricky part of the repair is going to be beveling of the fiberglass laminate on both sides; the cutout portion and the rest of the hull, at least one inch.

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Don McIntyre - MI
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Re: Deck Repair: Q9

Postby Don McIntyre - MI » Fri May 28, 2021 4:56 pm

Q9: in Figure 1, is the squarish section the void in the foam?

I cannot distinguish where the wood is, or where it's supposed to be.

Bonding new wood to the underside of the removed fiberglass section should be fairly easy. Just weight down the properly sized and resin coated replacement plywood. No need to go exotic, like vacuum bagging the part--it's just a flat piece. Make sure that the new wood is really flat and has no natural curve or bow.

Using non- epoxy resin for attaching would be a bit of cost savings. I'd recommend using epoxy for the cut repair on the topsides, minimal shrinkage over time.

dyoung16611
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Re: Deck Repair

Postby dyoung16611 » Sat May 29, 2021 8:36 am

The rotted wood [that was the reinforcement for the trapezoidal section section cut out of the deck] was not bonded to the foam.

It's difficult to see, but the foam will meet the underside of the gel coat skin around the sides and front portion. About 1 to 2-inch inches in from the sides and front, the foam level drops 1/2-inch to accommodate the plywood I removed before taking the picture.

The squarish section in the center [seen in Figure 1] appears to be from a prior repair; this is where there are potholes in the foam. They're not too large, perhaps 1/2-inch deep in areas.

ADHESIVE RESINS
I am using West System epoxy. The resin in called 105. The fast hardener is called 205. The slow hardener is called 206. I'm concerned about a short pot life, about the resin getting too hot, and about and not having enough working time, so this is why I plan to use t206 slow hardener. Also, it is getting warm here in Florida, which shortens the epoxy cure time.

FIBERGLASS CLOTH
I will use a fiberglass cloth with two sides; the front side has biaxial woven threads which weighs 17-ounces-per-square yard; the back side has random chopped strands which weigh 8-ounces-per-square yard. This product is called 1708 cloth. The 1708 cloth seems to be a common version of fiberglass material in my neck of the woods.

CHOPPED STRAND
I will use chopped strand matting (abbreviated CSM), which is like the back side of 1708 cloth. The chopped strand matting material is easy to pull apart and place where needed with some resin and a chip brush or fin roller. Chop strand matting material is what I'm considering using to bond the gel coat skin to the adjacent decking once I've feathered the edges.

I've considered making a non-skid mold from the piece of gelcoat I cut out, but that seems like a lot of work and am leaning towards grinding off the non-skid pattern on the entire deck and adding Awlgrip Griptex when I get to that stage.

Q10: are the step below a good repair plan?

  1. sand the foam down equal to the thickness of a couple layers of the 1708 cloth
  2. level the boat and pour some West System 105 resin and West System 206 slow hardener on the foam, laying the 1708 cloth across the entire area
  3. wet and install the new plywood
  4. lay more 1708 cloth across top of plywood and install the gelcoat skin [that was cut out earlier]
  5. fill the perimeter gap with West System 105 resin mixed with 205 hardener and a thickening material
  6. grind the perimeter within the channel only--not the non-skid
  7. lay some chopped strand mat or some1708 cloth across the perimeter cut that was ground down
  8. sand, fair, paint.

I want to avoid making a mold of the non-skid if possible.
1983 15' Striper

dyoung16611
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Re: Deck Repair: Six Questions

Postby dyoung16611 » Sat May 29, 2021 6:13 pm

deck3a.jpg
Fig. 3. A new piece of plywood is fitted into the cut-out section. Notice how the top of the wood is flush with the surrounding foam.
deck3a.jpg (13.62 KiB) Viewed 4802 times


Don--note the slight bow in the plywood on the right side. Your comment about ensuring the new wood is flat is relevant. I’ll need to make some more sawdust.
1983 15' Striper

Vance's Revenge
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Re: Deck Repair: Six Questions

Postby Vance's Revenge » Sat May 29, 2021 9:28 pm

For fairing, I had wonderful results with Total Boat's Total Fair epoxy-fairing compound. It mixes 50-50 and sands easily.

Another product I found to be terrific during my project is West Systems Six10. Six10 is thickened and mixes as it leaves the tube which gives you more time to work with it. It has terrific adhesion strength.

Also Six10 is the best material I found for filling gaps and faring radiuses. It is very expensive, but it is so easy to work with it makes beginner's work look like it was done by an expert.

jimh
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Re: Deck Repair: Six Questions

Postby jimh » Sun May 30, 2021 10:07 am

An idea for handling the aft cut line of the trapezoidal piece that was cut out: since you are going to be painting the boat and the original gel coat surface will be covered, you could add your own molded depression or gutter around the trapezoidal section you have cut out at the aft (longest) side. This should look better and more finished than just butting two areas of non-skid with a slightly ragged joint line.

jimh
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Re: Deck Repair

Postby jimh » Sun May 30, 2021 10:12 am

dyoung16611 wrote:The rotted wood [that was the reinforcement for the trapezoidal section section cut out of the deck] was not bonded to the foam.


Your observation is quite interesting. The foam layer looks like it was very close to or even in contact with the wood underside of the deck section that you cut out. Perhaps there was just enough gap to prevent a good bond from occurring between the wood and the foam. I would have expected that just prior to combining the two molded pieces, the hull and the liner, polyester resin would have been sprayed onto the wood to create an adhesive to bond with the rising foam. Perhaps just a bit more foam was needed to fill the gap or bit more mash of resin and chopped fibers on the wood.

Since the 1983-era when this boat was manufactured, Boston Whaler has improved their production process controls so that voids in the foam are less likely to occur.

dyoung16611
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Re: Deck Repair: Six Questions

Postby dyoung16611 » Mon May 31, 2021 7:19 am

Jim, thank you for the recommendation on how to address the seam along the aft edge. That’s about the only reasonable idea I’ve heard, other than making a non skid mold. As to the void between wood and foam, I suspect they were bonded originally, but not when the previous repair was made.
1983 15' Striper

jimh
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Re: Deck Repair: Six Questions

Postby jimh » Mon May 31, 2021 7:43 am

DYOUNG--I think you have a lot of experience working with fiberglass and resins. I am sure the repair will be well done. The soft area was probably due to a small defect in the original molding of the boat. When you are done, that area will be better than new.