hot-mop tar over plywood for budget houseboat hull construction?

Asphalt is a mixture of tar and aggregate.

Creosote - Wikipedia https://en.wikipedia.org/wiki/Creosote
"The two main kinds recognized in industry are coal-tar creosote and wood-tar creosote. The coal-tar variety, having stronger and more toxic properties, has chiefly been used as a preservative for wood; coal-tar creosote was also formerly used as an escharotic, to burn malignant skin tissue, and in dentistry, to prevent necrosis, before its carcinogenic properties became known.[4][5] The wood-tar variety has been used for meat preservation, ship treatment, and such medical purposes as an anaesthetic, antiseptic, astringent, expectorant, and laxative, though these have mostly been replaced by modern formulations.[citation needed]

Varieties of creosote have also been made from both oil shale and petroleum, and are known as oil-tar creosote when derived from oil tar, and as water-gas-tar creosote when derived from the tar of water gas.[citation needed] Creosote also has been made from pre-coal formations such as lignite, yielding lignite-tar creosote, and peat, yielding peat-tar creosote."

Asphalt concrete - Wikipedia https://en.wikipedia.org/wiki/Asphalt_concrete
"The terms asphalt (or asphaltic) concrete, bituminous asphalt concrete, and bituminous mixture are typically used only in engineering and construction documents, which define concrete as any composite material composed of mineral aggregate adhered with a binder."

 

This is a good explanation of the difference between tar and bitumen:

18 Difference Between Bitumen And Tar - Dream Civil https://dreamcivil.com/difference-between-bitumen-and-tar/

 

Using hot-mop tar over plywood for budget houseboat hull construction is generally not recommended. While it might be a cost-effective approach, it has several significant drawbacks that could compromise the integrity and safety of the hull.

1. Waterproofing: While hot-mop tar can provide some level of waterproofing, it may not be sufficient to prevent water from seeping into the plywood over time. Water intrusion can lead to rot and decay of the wood, causing structural issues and reducing the lifespan of the hull.
   
   
2. Flexibility: Plywood is not an ideal material for boat hull construction because it lacks the flexibility and strength required to handle the stresses and forces experienced in water. Over time, the plywood may warp, crack, or delaminate, compromising the structural integrity of the hull.
   
   
3. Weight: Hot-mop tar can add considerable weight to the hull. Excessive weight can negatively impact the boat's stability, buoyancy, and overall performance in the water.
   
   
4. Durability: Hot-mop tar is not as durable as other specialized marine coatings or materials used for boat hulls. It may not hold up well against the harsh marine environment, including exposure to UV rays, saltwater, and various weather conditions.
   

Instead of using hot-mop tar over plywood, it is advisable to consider more suitable materials and construction methods for building a budget houseboat hull:

1. Marine-grade plywood: If plywood is the material of choice due to budget constraints, consider using marine-grade plywood. Marine plywood is specially designed to withstand exposure to moisture and has improved waterproofing properties compared to standard plywood.
   
   
2. Fiberglass coating: Applying a layer of fiberglass cloth and epoxy resin over the plywood can significantly enhance the hull's strength, durability, and waterproofing.
   
   
3. Aluminum or steel: These materials are commonly used in boat hull construction due to their durability, strength, and ability to withstand marine conditions. While they may require more upfront investment, they offer greater longevity and reliability.
   
   
4. Design considerations: Opt for a hull design that suits the intended use and environment of the houseboat. A well-designed hull will contribute to better performance and safety on the water.
   

Building a houseboat requires careful planning, and it's essential not to compromise safety and quality for the sake of cost-cutting measures. If budget constraints are a concern, consider looking into alternative construction materials, seeking expert advice, and exploring used boats or boat kits that may offer more affordable options.

 

Ramu, thanks for that, and welcome to the Forum.

Why the sudden interest in an old thread?

Cheers!

 

That statement makes no sense. Plywood boats have been around for a century and it is a proven material for boatbuilding.