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[I need assistance in] distinguishing between materials like gel coat, fiberglass, and foam in areas of damage to my 1962 13-footer. The worst damage is at the front of the hull. (I understand this to be worrisome as it can mean that water has been forced into the damaged area. This certainly seems to be the case where there is a lot of loose material in this area.) At first I thought that this exposed brown surface (seen below) would be the foam core, but it is very hard.


Q1: Could the damage in Figure 1 be a layer of the fiberglass that the gelcoat is peeling off from?


Q2: is the exposed a brown textured surface seen in Figure 2 the fiberglass layer?

Thank you in advance for any assistance.

ASIDE: Hello. I am new to the forum and just purchased a 1962 13-footer that is in need of repair. I have read the following articles and am setting out to follow the "Whaler Way" in these repairs.

http://continuouswave.com/whaler/reference/whalerRepair.html
http://continuouswave.com/whaler/reference/repairInstructions.html

jamorr04 wrote:Q1: Could the damage in Figure 1 be a layer of the fiberglass that the gelcoat is peeling off from?

The damage seen in Figure 1 has certainly caused the gel coat layer to be chipped away. The impact has also caused considerable cracking. The exposed brown area is likely part of the first polyester laminating resin layer. Exactly what the original color of the laminating resin that was used in 1962 was and what color it would have in 2021 is unknown to me. The brown color is often associated with uncured polyester resins that have had contact with water.

A bit of background on the construction of a Boston Whaler Unibond hull may help you understand.

A Boston Whaler Unibond hull is built in a female contact mold. The mold surface is cleaned and prepared, and generally a mold release agent is sprayed into the female mold to prevent adhesion between the new molded part and the mold. The hull is then laid up into the mold, with the outer layer being the first layer.

The outer layer is the gel coat layer. The gel coat is sprayed into the mold. The mold is generally made in a color that contrasts with the gel coat color. The color contrast between the mold and the new hull gel coat helps the gel coat spray operator to judge the coverage of the gel coat layer thickness.

The multiple layers of the boat hull are intended to be laid up while the prior layer is still wet and in the process of curing. This results in what is called a primary-bond between the polyester resins of the two layers.

While the gel coat layer is still curing, the next layer is sprayed on top. This layer uses a laminating polyester resin and is often infused with small strands of fabric material that has been chopped to short lengths. This is a "chopper gun" layer. The orientation of the fibers is random. The fibers add strength. Again, the goal is a primary-bond with the gel coat layer

While the second layer is still curing, additional layers of cloth and resin are applied. The brown woven fabric seen in Figure 2 is part of this third layer.

In fiberglass laminate hull construction the essential element is to have a wet bond between layers that will cure at the same time, forming a strong adhesive bond. If some portion of the hull has insufficient resin, the bond will be inferior in strength, and the layers may de-laminate if subjected to impact forces. This appears to have occurred in the damage areas shown in Figures 1 and 2.

As for the apparent hardness of the brown layer in Figure 1, the exposed surface may be just cured polyester laminating resin. Also, perhaps the prior owner applied some sort of sealant or resin to prevent ingress of water at the exposed damage.

jamorr04 wrote:Q2: is the exposed a brown textured surface seen in Figure 2 the fiberglass layer?

The exposed brown textured surface seen in Figure 2 is part of the fiberglass laminate layer that used a woven cloth as the reinforcement material . This area of damage appears to have had a very poor bond to adjacent areas in the original lamination of the hull. Perhaps there was insufficient polyester resin infusion in that area. When the hull side sustained an impact, the upper layers of gel coat and laminate chipped away, apparently in a rather large area.

ASIDE: in 1962 the manufacturing process of a Boston Whaler Unibond hull was not controlled as precisely as done in later decades. Mixing of polyester resin with a curing catalyst might have been done with less precision as done in later decades. The lay-up process was done by hand, and variation in the laminates from hull to hull are expected. In general the weight of Boston Whaler boat hulls tended to increase from the initial weights cited, which is perhaps evidence that laminate thickness was generally increasing as production advanced from the earliest hulls. Also, high-force impacts will cause damage to any fiberglass hull.

Thanks for the great information.

Once I am able to flip the boat I will plan to chip and sand away the loose gel coat and further evaluate the hull with the information you provided.

Now that you've helped me identify the layers I will research the appropriate repair and painting procedures and report back the results.

I have begun the long process of sanding down old coats of paint. I have another unexpected finding.

While cleaning up the transom, I removed some loose and damaged fiberglass material. Under this fiberglass material was the original gel coat.

While inspecting further, I found that throughout the topside I am able to sand down to the original gelcoat and then find noticeably different material bonded over top. It is almost as if the boat has an entire extra layer of fiberglass.

Q3: is this a strange repair?

Q4: is the boat a work-boat version?

Q5: is the boat totally normal and I am crazy?

Possible additional evidence [of alteration of the hull from the original] is the lack of handholds on the aft of the transom; this goes against the research I've done.





Thank you in advance for any feedback.

[Moderator's note: in a thread with multiple images attached and multiple questions, the images should be identified with numbers as in Figure 1, Figure 2, and so on, and the questions may also need numbering in order to make them more clearly separated from other remarks that are not questions.]

Figures 3 and 4 above appear to show the original blue gel coat top layer of the hull has been covered by another top layer with a white hue.

jamorr04 wrote:Q4: Is the boat a work-boat version?

In my opinion the boat seen in Figures 3 and 4 was not originally laid up with two different colors of gel coat. The characterization of the surface texture of the present, white, top layer as "rough" is not typical for a top layer that was sprayed into the female contact mold as the first layer in the lay-up of the hull. If the white layer were the first layer, its surface would be completely smooth.

Hulls made to the Boston Whaler work boat specification did not have thicker layers of gel coat resin. Gel coat resin is brittle. It is usually only applied to a thickness of about 0.020-inch ("twenty mils"). If gel coat builds up to be thicker, as it can in concave surfaces in the mold, it becomes more prone to fracturing under stress. And, certainly, Boston Whaler would NEVER have sprayed a new layer of gel coat on top of a previously applied and fully cured layer of gel coat AFTER the hull was removed from the female contact mold.

My inference is the particular 13-foot hull you have acquired was considerably altered after it left the Boston Whaler factory by some previous owners. The methods used were not particularly appropriate, as evidenced by the poor adhesion between the original blue gel coat outer layer of the hull and the rough white new layer applied on top of the cured blue gel coat layer.

The other unfortunate effect of the added layer is added weight.

jamorr04 wrote:Is this a strange repair?

The "repair" is very strange.

jamorr04 wrote:Q5: is the boat totally normal and I am crazy?

The boat is certainly without any doubt NOT "totally normal."

I recommend you weigh the bare hull. The weight should give you some indication if there has been ingress of water into the hull and how much added weight has been contributed by the white rough surface that has been applied.

Regarding how to proceed, in my opinion attempting to restore this hull to anything close to its original gel coat by removing the added white rough surface will be quite a project and probably impossible to attain. If the hull seems structurally sound and has not accumulated excessive weight from ingress of water, it can be repaired and can become a useful small open 13-foot skiff. The hull and cockpit will need to be sanded and have all lose material removed so that a stable layer of laminate surface can be prepared to receive a new top coat.

For a demonstration of the process, watch the recorded presentation available at

Boston Whaler Crazing Repair
https://www.youtube.com/watch?v=pUOlWPvgLfQ

You will see a 13-foot Boston Whaler that is in much better condition than the hull under discussion here. The most informative part of the recorded presentation will show the use of fairing compound and new paint top coats. Before you can get to this phase of the repair, you have to remove all the loose material and generally fair the hull to a more uniform top layer. The presentation linked above is extremely well photographed and clearly narrated, which sets it apart from the usual shaky-camera and needlessly wandering and wordy narrations generally seen in amateur recordings. The three minutes are very much worth careful study.

I thought over the great advice I have received from this forum and headed back to the garage this weekend with the intent of deciding whether to go forward with prepping my "mystery layer" for paint or going all in on removing it and trying to get back to the original hull. At the center of the transom the "mystery layer" was separating enough that I could rip it off with my bare hands.



I was able to remove so much material by just pulling it off of the hull I decided to keep going. Eventually I needed to use a mallet and a wedge to keep it going but I was able to remove quite a bit. It's a little hard to see in Figure 6, but I quickly unveiled a center handhold filled in with some type of putty.



I worked my way around the top of the boat. Between the mallet and wedge and grinding I was successful in removing material down to the original gel coat or fiberglass. When I got the bow I found an even bigger mess. The slanted surface in the bow I previously was wondering about turned out to be very thickly overlayed with additional material. In the bow there was not only the white "mystery layer" but also foam or bondo or something to add a lot of thickness to the front of the boat.



For the most part I did not discover significant damage to the hull under all of the material removal but I'm worried about what I will find. There has to be some reason the previous owner did all of this.

As far as the original question intended to be asked in this thread: What is this mystery material? I am beginning to think it is either woven kevlar or fiberglass. It is entirely not saturated and really seems closer to drywall tape than anything I'd expect to see on a boat. Either way, in about four hours of work after committing to ripping out this material I had a bag that weighed 12 lbs.

Figure 7 appears to show damage to the foredeck at the bow, with the original blue deck laminate having suffered some fractures and some of the interior foam dark from mildew.

I think you are now committed to more work. You will have to repair the areas of damage to the hull deck that have been revealed by stripping off the top layer of mysterial white material. Then you will have to use filler and fairing compound to even out the surfaces, followed by careful sanding and fairing. Then the hull and deck will be ready for several coats of marine paint.

The previously mentioned and linked recorded presentation of repainting a Boston Whaler hull is still good guidance.