When I was examining boats in Europe, I found the most expensive boats often had the worse osmosis. I saw one very high end sail boat go from a million dollars selling price to less than $100,000, after out of water survey... There was a hole all of the way thru the laminate. One of the issues, there is that some of the best boats are laminated in Scandinavia. Then they go to the warm waters of the Med. Great combination for osmosis, There is another issue, which is rarely mentioned, and this is "floppy hull syndrome" Basically this is where osmotic water/chemicals, have migrated up the mat fibers, and then hydrolysis occurs, and eventually the stiffness of the hull is compromised. Another facet of this is a poor glass to resin ratio. I have never seen this in C Dorys. I have seen it in a number of older small sailboats (and I include some 40 footers in this category). A well built fiberglass boat can last a long time. The CG made two fiberglass river patrol boats in about 1942, and used them for 20 years. The boats were taken out of service, and panel sections were cut out, and compared with the deflection, crush, etc as panels which were laid up and tested at the time of initial layup. There was little change. I owned a fiberglass production 10' boat built in 1941--probably the first fiberglass production run boat built--and I "restored it in 1981--used it daily for 5 years. That same dinghy was seen in 2015--over 70 years after it was built, and still in good condition. But it was stored "dry", even though exposed to the "elements" it never sat in the water full time, nor did water accumulate in it. Incidentally, it was not gel coated, but painted.
Bottom Paint
- Thread starter jritsema
- Start date
When I was examining boats in Europe, I found the most expensive boats often had the worse osmosis. I saw one very high end sail boat go from a million dollars selling price to less than $100,000, after out of water survey... There was a hole all of the way thru the laminate. One of the issues, there is that some of the best boats are laminated in Scandinavia. Then they go to the warm waters of the Med. Great combination for osmosis, There is another issue, which is rarely mentioned, and this is "floppy hull syndrome" Basically this is where osmotic water/chemicals, have migrated up the mat fibers, and then hydrolysis occurs, and eventually the stiffness of the hull is compromised. Another facet of this is a poor glass to resin ratio. I have never seen this in C Dorys. I have seen it in a number of older small sailboats (and I include some 40 footers in this category). A well built fiberglass boat can last a long time. The CG made two fiberglass river patrol boats in about 1942, and used them for 20 years. The boats were taken out of service, and panel sections were cut out, and compared with the deflection, crush, etc as panels which were laid up and tested at the time of initial layup. There was little change. I owned a fiberglass production 10' boat built in 1941--probably the first fiberglass production run boat built--and I "restored it in 1981--used it daily for 5 years. That same dinghy was seen in 2015--over 70 years after it was built, and still in good condition. But it was stored "dry", even though exposed to the "elements" it never sat in the water full time, nor did water accumulate in it. Incidentally, it was not gel coated, but painted.
Bob, interesting your comment on never seeing osmosis in C-Dory boats. I just had some glasswork done on my TomCat by a local pro, (surface buffing). He commented more than once on how impressed he was with the quality of the glass. He rated it better than Sea Ray, and only slightly less than Tiara.
Interesting.
Interesting.
thataway":357sch4y said:
This. My boat is in Alaska, and I'm not moving it to Florida. It's a not really an issue in our harbor (now galvanic corrosion on the other hand...). I spoke to a lot of people before I had my bottom painted, and most commercial operators for many decades. Blisters a not really common in cold weather, and so epoxy is not the norm. I would concur it is a better method to use an epoxy barrier coat.
If I were to cruise or trailer my boat anywhere I would have made a different choice. I'm just want to clarify because it wasn't part of my initial post and so I may have provided bad advice inadvertently.
For what its worth, the cost was substantial, at least locally. Partly because it's not considered necessary any bottom painter charges a premium to apply an epoxy barrier.
Pardon on this polyester - vinyl ester talk. No study to my knowledge has
either more or less proven to be better for water intrusion than the other.
The main difference is strength. Both help prevent water intrusion.
Polyester resin + glass fiber is inferior to vinyl ester resin + glass fiber because
vinyl ester resin more closely matches the shear/strength quality of fiberglass
fibers compared to polyester resin. That's one reason why vinyl ester resin +
fiberglass costs more. Glass cloths, layup methods, resin:glass ratios and
vacuum bagging or not are another discussion.
The polyester resin in layups fail (crack, split, etc) before the glass fibers do under
stress. Vinyl ester resins fail eventually but closer to the fail points of the glass
fibers making vinyl ester/glass construction stronger than polyester/glass.
Aye.
either more or less proven to be better for water intrusion than the other.
The main difference is strength. Both help prevent water intrusion.
Polyester resin + glass fiber is inferior to vinyl ester resin + glass fiber because
vinyl ester resin more closely matches the shear/strength quality of fiberglass
fibers compared to polyester resin. That's one reason why vinyl ester resin +
fiberglass costs more. Glass cloths, layup methods, resin:glass ratios and
vacuum bagging or not are another discussion.
The polyester resin in layups fail (crack, split, etc) before the glass fibers do under
stress. Vinyl ester resins fail eventually but closer to the fail points of the glass
fibers making vinyl ester/glass construction stronger than polyester/glass.
Aye.
jritsema, just to clarify, I have never seen a "floppy hull" in C Dory. Osmosis can occur in C Dorys--and I did not say that I have not seen osmotic blistering. I have also seen what appears to be poor adhesion/bonding between the gel coat, and first layer of mat. This has resulted in blistering of the gel coat. Several boats had to have the gel coat removed, and then epoxy applied, with proper coating for either antifouling or trailering. This is a bit different than the osmotic blistering in the laminate--which involves the actual glass laminate layers.
Foggy, there is abundant scientific literature involving the water permeability of the various resins. (There are many different epoxies, vinyl esters [which has some epoxy characteristics, including cross linking], and polyesters.) The vinyl ester and epoxy also have less susceptibility to what is termed "hydrolytic attack".
Yes, Epoxy has better adhesive properties than vinyl ester resin, which has better adhesive properties than polyester resin. The chemistry and physical properties of epoxy, epoxy/vinly ester, and polyester resins, is not a simple subject. The various types of cloth, fiber materials (including kevlar, carbon fibers etc) is extremely complicated, and not an issue as simple as you attempt to make it. There are a number of books, as well as scholarly articles on the various properties of the multiplicity of resins.
Hull strength and quality does not boil down to: "Polyester resin + glass fiber is inferior to vinyl ester resin + glass fiber because vinyl ester resin more closely matches the shear/strength quality of fiberglass fibers compared to polyester resin. That's one reason why vinyl ester resin + fiberglass costs more.e"
A very high quality and strong hull can be and is made from polyester resin. As exotics--if you follow the current around the world race, there are an extraordinary number of structural failures.
There are advantages and disadvantages to vinyl ester resin--as well as epoxy.
Cost: For example one site gives a standard boat building polyester resin at $ 60 a gallon, Vinyl ester at $90 a gallon, and Epoxy at $115 a gallon. There can be considerable variation, including the manufacture, the quantity, and the specific characteristics of the resin. I have found polyester resin as cheap as $22 a gallon. But there are various qualities of the resin, is it Orthophthalic (older and more likely to have osmosis) or Isophthalic (better)? Boats built purely with vinyl ester resin cost more for several reasons--one is that resin is about twice as expensive as the polyester resin. The second is that the vinyl ester is a bit more difficult to work with--and thus labor costs are higher. Generally a boat built with the higher quality resin, will have better workmanship.
Some manufacturers will put a layer or two of mat or even cloth and mat, with vinyl ester resin as a water barrier under the gel coat. That may not always be sufficient to stop osmosis.
Scottbader company put out a handbook on various resins, and materials in 2005:
about 10 years old, but still a lot of good very basic information on the uses and types of materials.
Foggy, there is abundant scientific literature involving the water permeability of the various resins. (There are many different epoxies, vinyl esters [which has some epoxy characteristics, including cross linking], and polyesters.) The vinyl ester and epoxy also have less susceptibility to what is termed "hydrolytic attack".
Yes, Epoxy has better adhesive properties than vinyl ester resin, which has better adhesive properties than polyester resin. The chemistry and physical properties of epoxy, epoxy/vinly ester, and polyester resins, is not a simple subject. The various types of cloth, fiber materials (including kevlar, carbon fibers etc) is extremely complicated, and not an issue as simple as you attempt to make it. There are a number of books, as well as scholarly articles on the various properties of the multiplicity of resins.
Hull strength and quality does not boil down to: "Polyester resin + glass fiber is inferior to vinyl ester resin + glass fiber because vinyl ester resin more closely matches the shear/strength quality of fiberglass fibers compared to polyester resin. That's one reason why vinyl ester resin + fiberglass costs more.e"
A very high quality and strong hull can be and is made from polyester resin. As exotics--if you follow the current around the world race, there are an extraordinary number of structural failures.
There are advantages and disadvantages to vinyl ester resin--as well as epoxy.
Cost: For example one site gives a standard boat building polyester resin at $ 60 a gallon, Vinyl ester at $90 a gallon, and Epoxy at $115 a gallon. There can be considerable variation, including the manufacture, the quantity, and the specific characteristics of the resin. I have found polyester resin as cheap as $22 a gallon. But there are various qualities of the resin, is it Orthophthalic (older and more likely to have osmosis) or Isophthalic (better)? Boats built purely with vinyl ester resin cost more for several reasons--one is that resin is about twice as expensive as the polyester resin. The second is that the vinyl ester is a bit more difficult to work with--and thus labor costs are higher. Generally a boat built with the higher quality resin, will have better workmanship.
Some manufacturers will put a layer or two of mat or even cloth and mat, with vinyl ester resin as a water barrier under the gel coat. That may not always be sufficient to stop osmosis.
Scottbader company put out a handbook on various resins, and materials in 2005:
about 10 years old, but still a lot of good very basic information on the uses and types of materials.
Foggy asks about aluminum hulls. In my opinion there are some excellent hulls built in the proper grades of aluminum alloy. Steve Dashew's power boat designs are all built in aluminum currently. However, these have a work boat appearance. That is true of most of the aluminum hulls. Just like plywood, making compound curves is difficult, but can be done. There are many aspects to aluminum building beyond the alloy and finish, such as the framing, preventing water entrapment, also like steel, not drilling holes, but welding on fittings when ever possible. In work boat format, the aluminum hulls can be competitive price wise with the fiberglass. However, to yacht standards, the costs of fairing may be prohibitive.
In the small pilot house boats there are several I would consider: Wooldbridge, Duckworth, Almar, Armstrong, Kingfisher, Norvelle, Harbercraft, Defender-Safeboat--(these are on the used market, and could make a nice cruising conversion...Sea Raider, even Marinette. The latter might seem strange for an older cheaper aluminum boat--but I have seen some which have survived hurricanes and abuse... I sure I have missed some good hulls, and there are a number of low production boats--even Bar Tender has been made in aluminum.
In the small pilot house boats there are several I would consider: Wooldbridge, Duckworth, Almar, Armstrong, Kingfisher, Norvelle, Harbercraft, Defender-Safeboat--(these are on the used market, and could make a nice cruising conversion...Sea Raider, even Marinette. The latter might seem strange for an older cheaper aluminum boat--but I have seen some which have survived hurricanes and abuse... I sure I have missed some good hulls, and there are a number of low production boats--even Bar Tender has been made in aluminum.
I've seen hundreds of aluminum boats on the Inside Passage designed primarily for day-trip fishing. Most of the charter fishing boats in SE Alaska are aluminum. Seems like the simplest approach for a day-after-day hard-working low-maintenance reliable boat. The higher quality ones, and ones made into nice cruisers, are definitely not cheap.
We considered an aluminum cruiser when we moved from our CD22 to a larger boat, and looked at several. But for cruising cool northern waters, I prefer a quieter, warmer, dryer, more comfortable, (and prettier, to my taste) boat. FRP meets more of my needs.
We considered an aluminum cruiser when we moved from our CD22 to a larger boat, and looked at several. But for cruising cool northern waters, I prefer a quieter, warmer, dryer, more comfortable, (and prettier, to my taste) boat. FRP meets more of my needs.
Saxe Point
New member
Aluminum boats, particularly recreational fishing and work boats, are extremely popular and common out here on the West Coast of British Columbia. Nothing is more durable and requires less maintenance. But they are very expensive as compared to boats made of virtually any other material. Some of us refer to them as "precious metal"! Check out the Silver Streak boat website, to get an idea. Fantastic boats that are extremely well made, but also very pricey.
For those who have done bottom paint, particularly here in the PNW, what are you doing with the metal appendages hanging on the stern of your crafts? Things like outboard lower units, transducers, and trim tabs. Does the same paint work on them or does it need to be different.
I had good success with the Desitin (zinc oxide ointment) for my babies metal bottom parts, no fuzz, rash or sharp bumpy things. Sure, that worked for a one time treatment, (68 days in a row there) but not what I want to do for ever, every season, all the time.
The trim tabs, and permatrim seem like a different animal, stainless or aluminum., but they still grow stuff. What is the best treatment?
Harvey
SleepyC:moon
I had good success with the Desitin (zinc oxide ointment) for my babies metal bottom parts, no fuzz, rash or sharp bumpy things. Sure, that worked for a one time treatment, (68 days in a row there) but not what I want to do for ever, every season, all the time.
The trim tabs, and permatrim seem like a different animal, stainless or aluminum., but they still grow stuff. What is the best treatment?
Harvey
SleepyC:moon
Harvey, when we bottom painted, they used the same bottom paint all across the lower portions of the motor as well as the trim tabs. Basically carried across the same line. Both of these portions did collect barnacles while wet mooring for at least 6 months.
When we re-bottom paint this spring, I think we'll paint these metal areas with special paint made for metal below the waterline. Hopefully this works better. Especially on the trim tabs. I bought the special spray paint a couple of years ago but have yet to do it. This spring.
Peter
When we re-bottom paint this spring, I think we'll paint these metal areas with special paint made for metal below the waterline. Hopefully this works better. Especially on the trim tabs. I bought the special spray paint a couple of years ago but have yet to do it. This spring.
Peter
There are some bottom paints which are comparable with Aluminum. Those include TriLux 33, Vivid, Hydrocoat eco, Ultima Eco, spray cans of West Marine outdrive, Trilux 33 outdrew, Petit "Alumaspray Plus.
I try and keep the lower leg of the outboard out of the water. My Caracal, has a small area on the tip of the Suzuki 140 which is in the water, so that has a a number of coats of one of the outdrive paints on it. The C Dory gets the vivid applied to the trim tabs (except the zincs), and the outboard bracket. I can keep the rest of the outboard out of the water.
Be sure there is a good barrier on the aluminum before spraying. Probably on SS a coat of epoxy will give a better bond.
I try and keep the lower leg of the outboard out of the water. My Caracal, has a small area on the tip of the Suzuki 140 which is in the water, so that has a a number of coats of one of the outdrive paints on it. The C Dory gets the vivid applied to the trim tabs (except the zincs), and the outboard bracket. I can keep the rest of the outboard out of the water.
Be sure there is a good barrier on the aluminum before spraying. Probably on SS a coat of epoxy will give a better bond.
Harvey,
The information about the Pettit Hydrocoat ECO bottom paint, I applied last spring, says it can be applied to the areas you asked about. Thus far, I haven't tried it, but as I have plenty of paint left, I think this spring, I will start by trying some on the undersides of these areas. As mentioned before I'm very pleased with the ease of application on the normally applied areas & how it performed last year.
Jay
The information about the Pettit Hydrocoat ECO bottom paint, I applied last spring, says it can be applied to the areas you asked about. Thus far, I haven't tried it, but as I have plenty of paint left, I think this spring, I will start by trying some on the undersides of these areas. As mentioned before I'm very pleased with the ease of application on the normally applied areas & how it performed last year.
Jay
At the Seattle Boat Show I ran into some folks who do bottom paint. Who'd a thunk it, right? I actually talked to a few of them who would answer serious questions.
Anyone here have any experience with the Sea Hawk line of paint? They have the full meal deal, and have been around for 15+ years, and have some pretty major boat builders using their products -- Westport and Ocean Alexander are just a couple that I remember.
I am looking into that line comparing it to Vivid, which has been around for much longer.
Curious?
Harvey
SleepyC :moon
Anyone here have any experience with the Sea Hawk line of paint? They have the full meal deal, and have been around for 15+ years, and have some pretty major boat builders using their products -- Westport and Ocean Alexander are just a couple that I remember.
I am looking into that line comparing it to Vivid, which has been around for much longer.
Curious?
Harvey
SleepyC :moon
Another question for those who have bottom painted.
What did you do with the Brass Stem strip? I see 3 basic options.
1. Pull it off, fill the holes and then paint and leave it gone.
2. Pull it off, fill the holes, Paint and reapply it.
3. Pull it off, fill the holes, Paint and then apply a Keel Guard over the bottom paint.
Thoughts, and reasons please?
Harvey
SleepyC :moon
What did you do with the Brass Stem strip? I see 3 basic options.
1. Pull it off, fill the holes and then paint and leave it gone.
2. Pull it off, fill the holes, Paint and reapply it.
3. Pull it off, fill the holes, Paint and then apply a Keel Guard over the bottom paint.
Thoughts, and reasons please?
Harvey
SleepyC :moon
#4. Leave it in place, and paint over it. This is what I have done on all the boats and no issues.
If you pull it off, you will have to not only fill, but cosmetically blend the bow to the rounded profile which the brass strip gave. In my 22, the brass strip got up to the bow eye, so there would be an area to gel coat, and blend in.
If you pull it off, you will have to not only fill, but cosmetically blend the bow to the rounded profile which the brass strip gave. In my 22, the brass strip got up to the bow eye, so there would be an area to gel coat, and blend in.
thataway":2f5j1sbs said:
If you paint over it, how dies the paint maintain over time, on the brass?
OR, looking at #3. the KeelGuard would cover the profile void, after the screw holes were filled.
This is the one I am leaning toward, as I don't like the idea of painting over the brass strip and not having it painted underneath, on the gel coat.
Harvey
SleepyC :moon
journey on
New member
Bob, what do you use on underwater sensors such as the transom mounted depth sounder? Or do you have any on the 22? I'm asking because last summer the depth sensors ended up being covered in small barnacles whilst in Frisco. Never in the San Juans when we were there. Must be water temp and stagnant water.
Does regular copper bottom paint reduce the signal? I never thought about it before.
Boris
Does regular copper bottom paint reduce the signal? I never thought about it before.
Boris
journey on":2de08fpm said:
Good question. Please add the use of the baby diaper rash cream (Desitin) or another Zinc Oxide treatment in the answer. I used Desitin on the trim tabs and around the edges of the transducer last summer. I did not put it on the bottom of the sounder transducer, or on the outboards, but scrubbed them with a brush fairly often.
Harvey
SleepyC :moon
