Identify Hull Laminate Layer from Photograph: Hull Weight

[Ejay]

Fig. 1. Hull of 1987 13-footer. Note area in the

IMG_1418.jpg (96.64 KiB) Viewed 855 times

Figuure 1 (above) shows the hull of my 1987 13-footer after I have sanded off a layer of white paint and gray primer. In the photograph there appears to a white gelcoat which is rough and crazed, and below that layer is a darker [layer which appears as a green-gray hue in the photograph] which seems to be in very good shape. And there are also some areas whose color is more yellow. Also, note the crazing as seen in the on the right of the photograph [near the sponson runner].

Q1: is the crazing [seen in the] white color the original gelcoat?

Q2: or is the darker and smoother area the original gel coat?

I have twice crudely weighed [the apparently bare hull of this 1987 13-footer] using a bathroom scale at four resting points, and the total of the four weights was 306-lbs.

Q3: is a weight of 306-lbs what the weight of a 1986 13-footer should be?

ASIDE. I don't know the history of this boat but it seems to have good bones. I am confused by what I am seeing. [Restoration of this 1987 13-footer] seems like a fun winter project.

--Ej

[jimh]

ASIDE ON INTERPRETATION OF COLORS SEEN IN PHOTOGRAPHS

The colors shown in photographs are highly dependent on the spectrum of the light that was being used to illuminate the scene. The overwhelming yellow hue of the boat as seen in Figure 1 is probably due to the use of lighting using older incandescent lamps, or the photograph was taken near sunset or sunrise. The appearance of a shadow of the trailer winch post tends to indicate the light source was coming from near the horizon.

One way to help viewers interpret the color is to include in the frame of the photograph a small square of pure white color, such as a piece of white paper. This will give viewers a reference for the color hues seen in the photograph.

The best method to assess the color of the hull is to take a photo outdoors in sunlight near noon on a clear day, that is, when the sun is high overhead and not obstructed by clouds.

DETERMINING LAYERS OF TOP COATS AND THEIR TIERS

To assess the existence of multiple layers of top coats that have been applied over the original gel coat layer, you should carefully wet sand an area where you believe there are still more top coat layers present. Do the sanding in a motion that will produced a feathering in the depth of material removed so the outer areas of the sanded area will have less material removed and the center of the sanded area will have the most material removed. In this way you should be able to reveal each top coat layer color and texture as the depth of material removed increases.

The gel coat layer should be a white or off-white, and if you sand through that layer you will encounter an immediate color change to a distinctly different hue in the laminations below the gel coat layer, typically a greenish or brownish laminate color.

[jimh]

Q1: is the crazing [seen in the] white color the original gelcoat?

In Figure 1 the depth of each particular area that has been sanded off is impossible to know, so to interpret the amount of material removed at each location is impossible.

Q2: or is the darker and smoother area the original gel coat?

The original gel coat layer should be a pure white or a slightly off-white, not any sort of yellowish hue.

Q3: is a weight of 306-lbs what the weight of a 1986 13-footer should be?

The weight of a completely bare hull in c.1987 is not given in Boston Whaler literature, but the weight of a STANDARD 13 model is listed at 320-lbs. A STANDARD 13 would only have two thwart seats, so the amount of weight added to a bare hull by those two seats would be perhaps not more than 20-lbs. On that bais, your measurement of the hull weight at 306-lbs seems to be appropriate for a bare hull from c.1987 production.

For advice on the weight of a 13-foot hull, see the REFERENCE section article on the 13-foot hull in the REFERENCE section of the website. There you will find listings of hull weights.

The REFERENCE section of the website contains a great deal of information about Boston Whaler boats. Many new participants in the forum do not realize the amount of information about Boston Whaler boat that is NOT in the forum discussion.

The section of the website that contains information about Boston Whaler boat is located at

https://continuouswave.com/whaler/

The REFERENCE section is located at

https://continuouswave.com/whaler/reference/

The Boston Whaler 13-foot hull article is at

https://continuouswave.com/whaler/reference/13/

[Ejay]

Jimh--thank you very much for your insight.

Your mention of a white gel coat with possibly a light brown laminate layer below it, that seems to best describe what I am seeing.

--Ej

[jimh]

To comment a bit further: the mottled surface of the hull seen on the right side of Figure 1 and near the middle (vertically) of the image is difficult to interpret. I cannot imagine that portion to be the hull's original white gel coat layer. To me it looks more like a paint layer that was badly applied and has severe "orange-peel."

Significant damage to the gel coat usually comes from having been left out-of-the-water and sitting in sunlight for years, resulting the gel coat layer becoming very dry and brittle, and exhibiting cracking.

It might be possible that the boat and its bottom gel coat was left in the water for decades and has now produced osmotic blisters. You will know if the uneven surface seen in Figure 1 is due to osmotic blisters because typically osmotic blisters hold water inside, and when the blister is broken there will be a wet interior.