1978 SPORT 15 Gel Coat Damage

[OGSW20]

My 1978 SPORT 15 boat has many problems. The gel coat and laminate layers are damaged in several places. Sections of the gel coat deck have spider cracks and crazing.

Q1: How much of the existing gel coat layer needs to be sanded off before I can start the fairing process?

Q2: Do I need to grind out any or all of these small hairline cracks before I start fairing?

Q3: Once faired and everything is smooth, am I ready to gelcoat?

Q4: Or, is there another step I should take before spraying on the gelcoat?

Q5: Is there a primer used before gel coat?

Q6: should I change the color to white from Desert Tan?

Q7: should I re-do the gel coat on the entire bottom?

Q8: should I consider using paint instead of gel coat?

I am very new to this and want to make sure I only have to do this once. Here are some photos of what I am working with.

Fig. 1. Damage on keel.

keelRash_.jpg (23.62 KiB) Viewed 1620 times

Fig. 2. Large area with chipped-off gel coat exposing laminate.

bigChip_.jpg (7.95 KiB) Viewed 1619 times

Fig. 3. Typical spider cracking, crazing, and numerous drilled holes in deck.

crazing_.jpg (37.42 KiB) Viewed 1618 times

Fig. 4. Impact damage below rub rail.

rubRailDamage_.jpg (9.26 KiB) Viewed 1617 times

[jimh]

When large surfaces of the deck have crazing and spider cracking as seen in Figure 3, the repair of the cracks on an individual basis will be impossible.

The gel coat layer is thin. You cannot sand away the cracks and crazing without sanding away most of the gel coat layer.

The damage to the hull keel area and smaller areas with impact damage on the hull as seen in Figures 1, 2, and 4 can be repaired and top coated with gel coat resin that matches the original.

To learn more about how to repair a Boston Whaler Unibond hull, read these three articles for comprehension:

The Epoxy Cure
Minor Repairs With Epoxy
https://continuouswave.com/maintenance-logs/epoxy/

Repairing Hull Damage the Whaler Way
https://continuouswave.com/whaler/reference/whalerRepair.html

Boston Whaler Factory Instructions
Hull Patch Kits
https://continuouswave.com/whaler/reference/repairInstructions.html

You probably can restore the outside and bottom of the hull with those methods.

Because of the extensive cracking and crazing of the gel coat in the cockpit areas, repair using gel coat on individual cracks will not be practical. The entire deck area will probably need to be sanded to a firm base, faired, and then top coating. This process is shown in an excellent motion picture presentation. Watch the method at

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

In the demonstration, the deck is refinished in blue, but any color can be used.

Unless you have expert knowledge and experience in spraying gel coat resin onto large areas of a boat hull outside of a the layup mold, I would be cautious about using gel coat as the top coat for resurfacing the deck. Also, you will lose the non-skid pattern.

[Phil T]

What is the goal for the boat?

Are you looking for a museum restoration or get the boat usable but not concerned with how it looks?

Damage in photos 1,2 and 4 can be repaired with Locktite Marine Epoxy or Marine Tex patch repair kit.

The fine small cracks in photo 3 are typical spider cracks that are superficial and do not need attention. If you detail the boat after repairs with heavy cut compound, the cracks will not be as prominent.

Do not introduce water to the boat till all the open holes are sealed.

The rust stains can also be cleaned off.

[OGSW20]

What is the goal for the boat?

Hi Phil, I am not looking for [the boat to be restored] to be a museum piece. The boat will be my fishing boat. I would like the boat to look decent. I'm very detailed and have done many restorations and renovations for home and auto. Never done anything on a boat, but I'm sure I can make it look good.

Q9: What are the best ways of tackling this restoration?

I'm not familiar with gelcoat, but the cracks to me seem deeper than just surface cracks.

I plan to start sanding everything down on the interior. I want to start buying supplies.

So far I plan to use Totalboat TotalFair Compound and their gelcoat with wax for the topsides.

On the bottom, I may use Totalboat Polyester Structural Repair Putty to fill in all the gouges and chips.

Q10: Does this sound about the right way to go about this repair?

[OGSW20]

When large surfaces of the deck have crazing and spider cracking as seen in Figure 3, the repair of the cracks on an individual basis will be impossible.

The gel coat layer is thin. You cannot sand away the cracks and crazing without sanding away most of the gel coat layer.

The damage to the hull keel area and smaller areas with impact damage on the hull as seen in Figures 1, 2, and 4 can be repaired and top coated with gel coat resin that matches the original.

You probably can restore the outside and bottom of the hull with those methods.

Because of the extensive cracking and crazing of the gel coat in the cockpit areas, repair using gel coat on individual cracks will not be practical. The entire deck area will probably need to be sanded to a firm base, faired, and then top coating.

Thanks for the input jimh. I didn't think trying to repair the individual cracks would make sense. That is why I wanted to know how much of the gelcoat needs to come off before I could start fairing.

I'm not fond of the desert tan color, so I'm thinking I might change the color to the bottom while I'm doing this restoration. The top will likely be white, so it probably only makes sense to change the bottom to white as well. Just not sure if it requires redoing the gelcoat or painting it would hold up.

[OGSW20]

Do not introduce water to the boat till all the open holes are sealed.

I'm in a pretty dry part of California, however, I am not sure how long the boat has had those open holes from the previous owner. The previous owner had the boat for about 18 years. It doesn't appear that he was particularly concerned about filling those holes when he took out the original interior. The deck seems pretty solid. I do not notice any soft spots anywhere.

Q12: Should I be concerned about the open holes the boat has had over the course of the previous ownership?

If any water has gone in from those holes, it would be very minimal.

Q13: what can I do to assess the integrity of the hull before starting the work?

[jimh]

For answers to your many questions about repair procedures, see the prior comments and the links in them to detailed instructions on how to make repairs to a Boston Whaler Unibond hull.

Q13: what can I do to assess the integrity of the hull before starting the work?

Read the FAQ at Q3:

Q3: Is There Water in a Hull?
https://continuouswave.com/whaler/reference/FAQ/#Q3

Q1: How much of the existing gel coat layer needs to be sanded off before I can start the fairing process? ...how much of the gelcoat needs to come off before I could start fairing[?]

All unstable surfaces must be ground off or made stable in some manner before applying any top coat of any kind. If there is weakness and movement in any hull area, until this is repaired there is no point in applying a new top coat. The new top coat will just crack, like the old top coat did, with any instability or movement in the hull structure underneath it.

There is no possible way any reader can tell you exactly how much gel coat must be removed. You have to figure this out yourself, based on the condition of the gel coat.

Just looking at the deck surfaces in Figure 3, the spider cracks do not look very deep. The spider cracks occur with shrinkage of the gel coat due to failure to maintain the gel coat properly. Gel coat needs to be protected against continual UV exposure, against weathering, and against becoming too dry. For advice on gel coat care, see

Keeping Gel-Coat shiny and flexible. My Snake-oil treatment
https://continuouswave.com/forum/viewtopic.php?t=295

ASIDE: before asking or repeating the same questions, I encourage you to read the articles already given as hyperlinks, and also to read the FAQ. You can also use a well-crafted search to find prior discussions on any particular topic of interest. You can search from this page:

Searching continuousWave.com content
https://continuouswave.com/whaler/search.html

The CONTINUOUSWAVE.COM website has a lot of information content that is outside of discussions in this forum.

It is not practical to turn this thread into a comprehensive and well-written course on how to make gel coat repairs to older Boston Whaler boats. Such information is already provided in articles in the REFERENCE section.

[Phil T]

For new used-boat owners who have a boat that needs work, I always suggest new owners repair the critical items, detail the boat and use it for a year to determine what they really want to do to the boat.

After a year:
50% leave it as is and make small improvements,
20% do a complete restoration
30% sell the boat and find something in better shape.

The large cracks will need to be ground out and the filled and faired.

Understand the small hairline cracks shown in photo 3 are purely cosmetic. If you want them to not be seen, you have will need to grind off all the gelcoat.

If the interior is anything like the photos you sent and you don't want any cracks you are looking at 40 to 60 hours of grinding, filling, and fairing to prepare the interior for paint or gelcoat. A professional shop would charge about $5,000 to $7,000 to strip and paint the interior of the hull.

To acknowledge that the boat will not be worth the cost to restore it is important. Too many owners spend $10,000 to $20,000 and expect to sell the restored boat for that amount or more.

I suggest an experiment to help you assess your choices.

For the area shown in Figure 3 only:

• Mark the borders of the area shown in the photo with painter's tape
• Remove the transom eye
• Fill all the existing holes with Boat life's Life Caulk, marine sealant to keep the gunk out. Let cure.
• Wipe down the entire area in the photo with water and sponge removing all the loose dirt.
• Detail the area using 3M Heavy Duty Compound on a wool bonnet attached to a variable speed buffer. Work the area for at least three hours.
• Apply 3M Finesse-it II to the area using a wool bonnet for two hours.
• Wipe with a lint free towel.

Take a photo and post before and after photos side-by-side.

If you do decide to remove the gelcoat and paint, we will support you.

[jimh]

For new used-boat owners who have a boat that needs work, I always suggest new owners repair the critical items, detail the boat and use it for a year to determine what they really want to do to the boat.

Very good advice. Unless the primary purpose of buying a boat that needs restoration is to have a project to work on for hundreds and hundreds of hours, the usual purpose of buying a boat is to get out on the water and enjoy boating.