CONTINUOUSWAVE

Hi all. I just bought an old Nauset 16; it’s titled as a 1972, but the stencil suggests it’s a 1965, so who knows. I am trying to get it ready for the water. This is the first motorboat in our family, so I had hoped to run it pretty much as-is this summer, to get the chance to see how it worked for us before we thought about upgrades, repairs, or the like. However, after spending some time getting the bottom ready for paint, I’m a little concerned that I might need to do something more than just bottom paint--especially since we’ll be keeping it on a mooring.

Here are some photos:
https://www.dropbox.com/sh/67ux9hytjxyjgq5/AACWcIAcaMf9j3nQz-8ip5Wha?dl=0

As you can see from the pictures, there is a lot of cracking, crazing, and pitting. (I’m not sure what it’s called — perhaps there’s some of all three). I’m not concerned with the appearance (at the moment), but I was not sure whether the condition of the bottom gel coat poses a risk for letting water into the hull.

So, does it look like I need to do something more than just painting the bottom (with an ablative paint) this year? If so, what do you recommend? And is there a quick and dirty option that would get us through the summer (even if it had to be undone before doing anything more permanent)?

From what I’ve read, the obvious answer is a barrier coat (something I conceptually understand but have no experience with). That seems like a good idea at some point, and may actually have been done on this boat before--is that the black coating left on the bow? But all the descriptions I’ve seen for how to apply it involve significant preparation, more than I think I have time to do now (or at least more than I'd prefer to do now).

What happens if you do sub-optimal preparation?

Does [a barrier coat] not work at all?

Or does it just not last as long?

I appreciate that shortcuts rarely workout well, but I’d love to get to use the boat for a while before investing any serious time or (more) money. So throwing away a few hundred on a coating that only lasts a year or two might be a good investment (although I’ll have to think about it).

Longer term, it would be nice to clean it up a bit, so any advice on that would be appreciated as well. But I know there are other threads and resources that cover that sort of thing. And I can ask specifically about that later, when it's more appropriate.

Thanks for any advice you can offer!

Best,
David

Your pictures show some sort of deep pits on the hull surface that is below the water line. If the depth of pits is enough to extend below the gel coat layer and expose the underlying laminate, there is a good chance the boat could take-up water.

The problem with applying a "temporary" barrier coat is that ultimately you will have to sand away that barrier coat when you undertake a proper restoration of the hull bottom.

The simplest solution for your situation is to just not leave the hull in the water when you are not using the boat, until you get a chance to really restore the hull bottom. Launching and loading a 16-footer is really not difficult, and you can probably get away with using the boat as it stands, as long as you don't leave it in the water 24-hours a day for three or four months.

Thanks for the reply! Trailering does sound like a nice, simple solution, but it would actually come with problems of its own, since we don't have a vehicle that can haul the boat. So we'd be racking up a bunch of IOUs to our friends. :)

Would I (as a novice) be able to tell whether it's actually a problem? Is there something I could look for (like exposed fibers) that would be a tell? Or does it need a more experienced eye to differentiate between gel coat and laminate with a boat of this age and condition?

Also, do you have any sense of how long it is safe to leave in the water, assuming there is some exposed laminate? Is anything more than overnight asking for trouble? Is a week okay? Or is that just as risky as a few months?

Thanks,
David

My basis for comments about barrier coats comes from the recommendation of Boston Whaler. I have reproduced the owner's manual for two size ranges of classic Boston Whaler boats in the REFERENCE section. For advice on bottom paint, see

http://continuouswave.com/whaler/reference/manual9-17/maintenance.html#bottom

There you will find the following:

Any boat left in salt or fresh water for more than a few days should have the gelcoat surface protected with a two-part epoxy paint followed by an anti-fouling paint. This will retard marine growth and help protect gelcoat from possible blistering. DO NOT LEAVE YOUR BOAT IN THE WATER FOR ANY EXTENDED TIME WITHOUT BOTTOM PAINT.

In choosing the type of anti-fouling paint, consult with your friends or dealers and purchase the type most effective or most popular in your area. Mask the hull and apply the anti-fouling paint according to the specific instructions of the paint manufacturer. Most will recommend priming or etching the gelcoat with a wash. Do not short cut this or the anti-fouling paint will not adhere properly.

My own practice is to very seldom leave the boat in the water for more than a day. My boat's hull has no anti-fouling paint and has never had any applied. There also has never been a barrier coat applied. About once or twice a year the boat may sit in the water for several days, perhaps as long as eight to ten days, while we are living aboard and cruising on one of our summer trips. But those trips are in cold, very clean, pure, open freshwater, where there is little opportunity for any marine growth and no staining from tannin in the water. After any long duration in the water, the boat will typically sit on its trailers for several weeks.

The purpose of the anti-fouling paint is to retard marine growth. If you are boating in tropic saltwater the rate of marine growth on an unprotected hull bottom is quite impressive. In a week you can have crop growing.

The purpose of a barrier coat is to prevent water from passing through the gel coat layer and getting into the resin and laminates. Gel coat is not a completely waterproof barrier. Fiberglass boat hulls that sit in the water for very long periods have been known to develop osmotic blisters. For a discussion on the causes of osmotic blisters, read this article, again available in the REFERENCE section:

http://continuouswave.com/whaler/reference/theCausesOfBoatHullBlisters.pdf

On your particular Boston Whaler boat hull, the defects which appear as pits may actually have been osmotic blisters which have popped open.

To better understand how a Boston Whaler UniBond hull is made, read these articles, again from REFERENCE:

Original Design and Conception
of the 13-foot Whaler Hull
http://continuouswave.com/whaler/reference/13/originalHullDesign.html

BOSTON WHALER FACTORY TOUR
Where Legends Are Made
http://continuouswave.com/whaler/reference/factory.html

There are three levels of concern about water intrusion into the hull of a Boston Whaler boat. At the first level, the concern is for contamination of the gel coat layer, as mentioned above, with the possible result of osmotic blisters. This sort of water intrusion can occur on a gel coat layer that has no physical damage, that is, a layer that appears intact and like new. The remedy is to use a barrier coat of epoxy. Epoxy is generally considered to not permit any water to pass through it.

The next level of concern is for intrusion of water as a result of damage to the gel coat layer which exposes the underlying laminate and resin layers, and, if the damage is sufficiently deep, can expose the foam layer. The construction of a Boston Whaler boat is done with the UniBond hull method. The outer hull consists of a relatively thin lay-up of fiberglass, consisting of a gel coat resin layer that is about 0.020-inch thick, then layers of fiberglass resin with chopped fibers and some fiberglass cloth. The total thickness of the hull fiberglass varies with the exact location, but in general won't be as thick as you might expect. The boat is made by laminating together two hull sections, an outer hull and an inner hull or liner, then filling all the space between them with foam. This creates a strong but light structure.

If either the outer hull or inner hull-liner are physically damaged, and the gel coat is chipped away to reveal the underlying laminate layers or the foam, a point of entry for water is created. Water can--and will--begin to soak into the inner foam filled area, causing the hull to gain weight and also weakening the structure.

In your specific case, you should inspect the pits and other area of damage to assess how deeply those points of entry penetrate. If they go though the gel coat layer and expose underlying laminate layer, those layer may begin to soak up water. If the foam is exposed, it is almost certain the foam will soak up some water.

The third level of concern is for water intrusion which occurs below the water line on a running surface where the speed of the boat travelling through the water will tend to force water into the opening. When this occurs the water can begin to break apart the adhesive bonds between the foam and the laminate layers. Loss of bond between laminate layers and foam results in a major loss of structural strength. It is called delamination. The thin hull layers delaminate from the foam, usually creating even more effective scooping of water under pressure into the hull and causing the rate of damage to increase.

On your particular boat you are already at the first level of risk. The hull is not being protected by anti-fouling paint or a barrier coat. You must now assess if you are at the second level or risk, with exposed areas of the underlying laminate available for water to enter. You should also look carefully at the underwater running surfaces to make sure they do not have points of entry for water to forced into the inner hull under pressure.

To held identify the layers, you can generally expect them to have different colors:

--gel coat layer will be white on the hull and sometimes blue in the cockpit; this layer is very thin, about 0.020-inch;

--the underlying laminate layers are usually a greenish color; this layer is usually about 0.125-inch or thicker, perhaps 0.5-inch in very high stress areas like the keel;

--the foam layer is usually white or gray or brownish; this layer can be many inches thick as it extends and fills the entire space between outer hull and inner liner.

Your boat suffers from severe blistering. The blisters have opened, and much of the original gelcoat is damaged, or just plain gone. The best approach would be to soda blast the bottom, fill all the holes, etc. with thickened epoxy, and then apply a 5 or six coats of epoxy. You are going to need many gallons of epoxy. US Composites in Florida has the best epoxy, and the best prices.

You need to ask yourself "Is it worth it?". That hull is in very poor condition. What is the interior like? Does the boat have sentimental value or family history? You may be better off [in terms of] time and money with another boat that has been taken care of and doesn't need as much work.

I reviewed the images of the hull available at the linked hosting site. On this second visit I noticed that the gel coat layer of the hull above the waterline shows a lot of cracking and crazing. Gel coat layers in that condition generally cannot be restored by abrasion and removal of the cracks because the depth of the cracking is too great and the thickness of the gel coat layer is not deep enough to permit them to be rubbed out. Also the total number of cracks would prohibit individual repair and filling. The usual method of restoration of hulls with extensive cracking and crazing in the gel coat layer is to apply a new topcoat of paint. Of course, the application of paint is the last five-percent of the work, as the surface preparation will require consideration work to seal, fill, and fair the surface, and then to apply undercoat or primers--that will be 95-percent of the work.

davet--it's unfortunate that every Spring we see folks on boating sites that (unknowingly) bought a boat "cheap" that required significant work. The guys here won't steer you wrong, so pay attentio.

Is there a chance you can find a marina that has what's called "dry stack". That is, they put the boat in and out of the water on-demand. I did this with a 21-footer I had. I'm 20-minutes from the water, so I'd call before leaving and the boat would be in (via fork truck) before I arrived at the marina.

It's the only solution I can think of in your situation. It's also more affordable than a slip and potentially your only solution (for use this boating season), given the condition of the hull.

Ah well. Live and learn. Thanks for all the feedback! I think we're going to push ahead with this boat, largely because it takes us forever to make decisions about what to buy, so we probably wouldn't get around to selling and buying a new one before 2020. (I exaggerate, but not by much...) And while it certainly does seem easiest to just not store it in the water, doing a dry stack or trailering it just doesn't seem like it'd work for us, in part because our mooring is in walking distance and the dry stacks are not.

So we're thinking we'll take it to a marina and have them put on a barrier coat. Although this would eventually need to be removed if/when we did more extensive repairs, am I interpreting the comments correctly that a barrier coat would get us through a few years? Or are y'all saying that a barrier coat is not sufficient for a hull of this condition? (I was getting confused about whether the advice to not put it in the water was in relation to having just bottom paint or anything besides a full restoration.)

Anyway, this all might turn out to be a disaster, but at least we'll get some valuable experience about what not to do next time!

If you plan to hire out the work to restore an older boat like a Boston Whaler boat, I think you will be in for a shock. You'd end up spending more than it would cost to buy a new boat. When you take the boat to a boat yard for repair, be sure to get a written contract on the cost before authorizing any work.

You should also look at a recorded presentation on youTube which will give you some ideas on how to refinish the hull:

https://www.youtube.com/watch?v=pUOlWPvgLfQ&t=33s

Don't be scared away! I have been through this procedure three times. A 1967 13 footer, a 1970 16.5 footer and I now have a 1979 17 footer. Each one of these hulls had the exact same concern as yours does. Lets face it, these boats are old and are meant to be used. They were built really well but the previous owners didn't take care of them and now its your turn.

Do this:

Clean that hull as best as you can, scrub and wash and then give your self a day to reciprocal sand away any loose bottom paint or old gel coat that is loose. Then clean it again. Let everything dry for a week and then roll on a coat of Interlux two part epoxy prime kote. Follow the directions exactly and roll on at least 3 coats. Twp part expoxies are tough. Mix them really well. Don't worry about the hull texture. As the coats build up, they will encapsulate the gel coat and soften out the surface. The edges of the blisters will round out and your hull will feel smoother. I take it up the sides and transom, all the way to the rub rail flange.

Let everything dry and then add a anti-fouling paint. Two coats at least. You now have 5 coats of build on your hull. This effort will take about two weekends of time.

With five coats you will get at least three years of good use in a water storage condition, I do suggest you have the bottom scrubbed by a diver once a month or you can do it.

The total cost of this will be about 300- 400 dollars, paint, brushes, trays, rags, etc. You will have a nice boat once its done. Get a nice 70 HP four stroke for it and you are set. Also, your hull actually looks pretty good. The ones I have had typically have gigantic keel holes from improper trailer setup or rock groundings. I have spent months removing keels and foam and then glass and resin packing the voids to rebuild a keel.