1978 Hourston Glascraft Restoration

gunnerlove said:
Coosa. A wonder material intended to replace plywood that is not as strong as plywood but easily exceeds 4x the cost.
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Anyone who uses wood core material for a transom or stringers is living in the stone age- I'm sorry. A lot of you will hate me for saying that but I'm 100% right and there is no arguing it. Wood in areas of boats that can get wet is a compromise in this day and age when you have other betetr options.

https://coosacomposites.com/the-coosa-advantage/ one of many options...

Using wood is sloppy when there is a better material. I would never go to all the effort time and itchiness to put in a product that will fail long before the rest of the boat would. My 20ft Hourston is from 1988 and I removed its second set of rotten stringers from her in 2018 before replacing it with foam core stingers and Coosa transom with 1708 and epoxy. For the project cost to upgrade to those materials is a fraction of the total costs and I don't have to worry about my core turning to mush. My only regret is not adding another 6 layers of 1708, because why not.

If you want to do a subpar repair for a boat you don't plan on keeping then use the wood. If you plan on doing something at least halfway properly then use good core, save money and use polyester resin if you have to.
 
We add structure to a hull with the intention of stiffening it. Plywood has a 4 x greater resistance to deflection and double the resistance to compression of Coosa. You can use it in place of wood but not as a direct swap as you need to increase the layup in and over it to achieve the same resistance to deflection people would call strength. I am sure we can agree that without a doubt a bonded one piece fiberglass grid system is the best option we have for adding structure to a boat. Anything less is cutting corners and we should feel shame for considering it.
 
Iworkupnorth said:
the transom is a 1.5 inches at the main part and looks 3/4 on the sides. I'm planning on marine grade ply on the back and Douglas fir for the stringers fully encapsulate everything in epoxy and 1908. was thinking of pl to set the strings but not sure. there's a pl out there that bonds we'll and stays flexible and I can fillet the sides pretty good prior to glassing.
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I would bed the stringers in thickened epoxy then you can let it squeeze out and filet while its still green then you wont have any bonding issues with your fillets and you know you have full contact without hard spots. Pl might lose its bond strength quickly and interfere with the epoxy bond in the fillet 5200 would work better but also wont bond with the epoxy. Don't try to get the round out of the transom our it will crack the hull or cause severe crazing and spider webs at the least, if you take a look at an inboard model you will see its a significant shape and it helps give the skin strength as opposed to being flat across. I would use three layers of half inch ply with thickened epoxy applied with a 3/16 v notch trowel between skins you can temporarily use drywall screws and plywood washers through the holes in the transom to suck them together and to the transom. This way you only have to skin the final layer and will have the strength in the core as it was intended. Over drilling and filling the holes with epoxy will be one of the easiest things on your project plus its an outboard so not really that many holes to fill. With the stringers just seal the bottom as you bed it and encapsulate when you do the tabbing 10 ounce cloth will work better than 1708 for tabs because 1708 doesn't bend well and is used for decks and flat surfaces once you're in tight radius country best to use cloth three layers staggered for the tabbing. Be careful that you get epoxy compatible fabrics most 1708 is for use with poly.
 
Iworkupnorth said:
did you have your full information on this site what you did? I got to find it because I really like the approach you took and will help me out so much
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Sorry I missed this, I have been away from the keyboard for a very long time, I think if you look under "20' Hourston autopsy" it has a lot of notes.
 
Fritz said:
Sorry I missed this, I have been away from the keyboard for a very long time, I think if you look under "20' Hourston autopsy" it has a lot of notes.
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I see this post has also been hijacked lol, you poor *******.

I read books written by people that build boats and have been building boats for decades. There is a little thing also called engineering. These boats were designed for active stringers not passive stringers. And my boat lasted for 43 years without a structural failure (the best proof of engineering) and had 2300hrs on the Hobbs meter (which still works).

Great books to read are the following:

1. Fibreglass boat repair and Maintenance from West Systems (Free Online)
2. Marine Design Manual for Fibreglass Reinforced Boats by Gibbs and Cox (Free Online)(pay particular attention to the section on laminates)
3.The Gougeon Brothers on Boat Construction (Free Online)

All of these books use wood in their engineered structure.

I am not telling anyone what to do. It's an 18' Boat and will probably be the gateway to a larger craft. Is spending thousands on boat so the next three owners get to enjoy it worth it? I hate to say it but I think these boats will have ended their useable life cycle in another generation.
I also have a young family and did the best I could with the finances I had and within the ideals of the economy of effort.

Is using wood sloppy? Or Cave man? I don't think so. And Anything that is used in Seawater will eventually turn into junk.

Wood is natures composite! According to the Laboratory testing that has and is still being conducted by the Gougeon Brothers (West Systems) and I quote: Wood exhibits unusually high fatigue resistance and a considerably high percentage of this capability is fortunately available for a long fatigue life. This is not surprising when one considers that nature spent millions of years evolving trees in dynamic adverse environments. Some trees are more than 2000 years old and if one calculates the stresses involved in that span there are millions of stress cycles.

Douglas fir Marine Plywood is stronger than Coosa.

The Propaganda videos and forum halfwits that show the piece of Coosa being beaten with a hammer on concrete have missed the fact that if you beat a rubber strap or a kitchen sponge with a hammer it won't splinter either. Coosa is an amazing product and if you read their literature they tell you it will absorb water. No it does not rot. Yes it is buoyant (but so is wood). It is also lighter, but not by much. The other reason why the original boat builders used wood was because it was heavy. Hourston bragged in their 90's ads that they used Doug Fir Stringers. Part of the magic ride of these 70's boats comes from the hefty weight right at the lowest point of the boat.

I am really disgusted and disappointed with posts on this site recently where somebody building probably one of their first boats under a tarp in their driveway is being vultured and brow beaten to align with someones well, uneducated and ill suited opinions.

I built my boat to enjoy my girlfriend on, not for the next buyer (when I'm in my 80's) to enjoy his girlfriend on.

Again, I am not telling anyone what to do. If you are telling people what to do it's probably guilt from spending too much money.
 
Fritz said:
I see this post has also been hijacked lol, you poor *******.

I read books written by people that build boats and have been building boats for decades. There is a little thing also called engineering. These boats were designed for active stringers not passive stringers. And my boat lasted for 43 years without a structural failure (the best proof of engineering) and had 2300hrs on the Hobbs meter (which still works).

Great books to read are the following:

1. Fibreglass boat repair and Maintenance from West Systems (Free Online)
2. Marine Design Manual for Fibreglass Reinforced Boats by Gibbs and Cox (Free Online)(pay particular attention to the section on laminates)
3.The Gougeon Brothers on Boat Construction (Free Online)

All of these books use wood in their engineered structure.

I am not telling anyone what to do. It's an 18' Boat and will probably be the gateway to a larger craft. Is spending thousands on boat so the next three owners get to enjoy it worth it? I hate to say it but I think these boats will have ended their useable life cycle in another generation.
I also have a young family and did the best I could with the finances I had and within the ideals of the economy of effort.

Is using wood sloppy? Or Cave man? I don't think so. And Anything that is used in Seawater will eventually turn into junk.

Wood is natures composite! According to the Laboratory testing that has and is still being conducted by the Gougeon Brothers (West Systems) and I quote: Wood exhibits unusually high fatigue resistance and a considerably high percentage of this capability is fortunately available for a long fatigue life. This is not surprising when one considers that nature spent millions of years evolving trees in dynamic adverse environments. Some trees are more than 2000 years old and if one calculates the stresses involved in that span there are millions of stress cycles.

Douglas fir Marine Plywood is stronger than Coosa.

The Propaganda videos and forum halfwits that show the piece of Coosa being beaten with a hammer on concrete have missed the fact that if you beat a rubber strap or a kitchen sponge with a hammer it won't splinter either. Coosa is an amazing product and if you read their literature they tell you it will absorb water. No it does not rot. Yes it is buoyant (but so is wood). It is also lighter, but not by much. The other reason why the original boat builders used wood was because it was heavy. Hourston bragged in their 90's ads that they used Doug Fir Stringers. Part of the magic ride of these 70's boats comes from the hefty weight right at the lowest point of the boat.

I am really disgusted and disappointed with posts on this site recently where somebody building probably one of their first boats under a tarp in their driveway is being vultured and brow beaten to align with someones well, uneducated and ill suited opinions.

I built my boat to enjoy my girlfriend on, not for the next buyer (when I'm in my 80's) to enjoy his girlfriend on.

Again, I am not telling anyone what to do. If you are telling people what to do it's probably guilt from spending too much money.
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I'll be using wood, lasted 43 years without really no issues. it looks pretty dam good for 43 years old, especially when you have to use a chisel to get out most of the transom lol
 
steeler said:
I would bed the stringers in thickened epoxy then you can let it squeeze out and filet while its still green then you wont have any bonding issues with your fillets and you know you have full contact without hard spots. Pl might lose its bond strength quickly and interfere with the epoxy bond in the fillet 5200 would work better but also wont bond with the epoxy. Don't try to get the round out of the transom our it will crack the hull or cause severe crazing and spider webs at the least, if you take a look at an inboard model you will see its a significant shape and it helps give the skin strength as opposed to being flat across. I would use three layers of half inch ply with thickened epoxy applied with a 3/16 v notch trowel between skins you can temporarily use drywall screws and plywood washers through the holes in the transom to suck them together and to the transom. This way you only have to skin the final layer and will have the strength in the core as it was intended. Over drilling and filling the holes with epoxy will be one of the easiest things on your project plus its an outboard so not really that many holes to fill. With the stringers just seal the bottom as you bed it and encapsulate when you do the tabbing 10 ounce cloth will work better than 1708 for tabs because 1708 doesn't bend well and is used for decks and flat surfaces once you're in tight radius country best to use cloth three layers staggered for the tabbing. Be careful that you get epoxy compatible fabrics most 1708 is for use with poly.
Click to expand...
when you put that first layer of ply on the transom and wedged it in there until it cured, when you pulled the supports did the plywood try and straighten out again and pull that convex shape inwards? did you leave them on particularly long to have some of the wood fibers settle naturally to that shape rather than just a curing time prior to removing them?
 
I replaced all the fasteners on my rubrail it’s just time consuming because it’s like a 100 stainless bolts lol on my old 1978 Hourston I rebuilt. For a vin number there on the back
Top Right on the transom.
 

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Will be a great boat once again when finished. Personally I would have removed rub rail and entire top cap first, but glassing that should splash-well back in should be a blast lol.
I do believe that convex in the transom was factory on those vintage hourstons, albeit increased over the years with soaked plywood and a four stroke hammering away back there.
Just score each sheet of plywood vertically with a skillsaw to let it flex into the convex easier.
Nothing wrong with using wood, if glassed properly will last another 40 years. But the composites out today will last forever.
It’s a big job that I couldn’t imagine not doing inside a shop, enjoy!
 
Doubleheader said:
Will be a great boat once again when finished. Personally I would have removed rub rail and entire top cap first, but glassing that should splash-well back in should be a blast lol.
I do believe that convex in the transom was factory on those vintage hourstons, albeit increased over the years with soaked plywood and a four stroke hammering away back there.
Just score each sheet of plywood vertically with a skillsaw to let it flex into the convex easier.
Nothing wrong with using wood, if glassed properly will last another 40 years. But the composites out today will last forever.
It’s a big job that I couldn’t imagine not doing inside a shop, enjoy!
Click to expand...
 
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