10 Best Boat Flotation Foam of 2025

Tested and Reviewed: Top 10 Boat Flotation Foam deals with expert ratings from 8.1 to a perfect 10

March 2026 Edition

Editor's Choice

9.7

Oycevila

2 Quart Kit Marine Flotation Foam with Gloves, 2 Lb Density Polyurethane Expanding Foam for Fence Gap Filling, Reinforcement, Closed Cell Pourable Polyurethane for Boat Flotation, Insulation

Free Shipping

Editor's bottom line:

“This boat flotation foam is the best one we tested. In terms of quality, brand and price, we couldn't ask for more.”

Main Highlights

EXCELLENT FLOTATION SUPPORT: Expanding foam for posts when cured, fence post foam creates a strong, closed-cell structure that traps air, contributing to the flotation capabilities of marine vessels and structures. This feature is crucial for ensuring that boats and marine structures remain afloat, making it a popular choice for manufacturing and repairing sailboats, kayaks, canoes, and other watercraft.
STRENGTH AND DURABILITY: Upon mixing the two components, the expanding foam expands significantly, allowing it to fill voids and cavities effectively. T Despite its lightweight nature, polyurethane pour foam is remarkably strong and capable of withstanding harsh marine conditions, including impacts and constant exposure to saltwater.
INSULATION PROPERTIES: The flotation foam's insulating properties help maintain temperature stability within boats, making fence post foam ideal for insulating fish boxes, bait wells, and marine refrigeration units. This feature enhances the comfort and functionality of marine vessels, especially in extreme weather conditions.
VERSATILITY IN APPLICATION: This liquid foam can be used in a variety of marine applications, not only for buoyancy but also for insulation, soundproofing, and vibration dampening. Marine polyurethane expanding foam is easy to use and ability to conform to any shape or space make it a versatile choice for both construction and repair work in the marine industry.
PROFESSIONAL TECHNICAL: 1:1 mix and stir evenly, the working time before foaming is about 45 seconds. Apply in layers for thicker applications, allowing each layer to cure before adding the next. Make sure to cover the entire surface evenly.

Show Price

Picked by 397 people today

9.5

TotalBoat

TotalBoat 2 Lb Density Expanding Foam Kit, 2 Part Closed Cell Pourable Polyurethane for Boat Flotation, Insulation, Reinforcement and Void Filling (2 Gallon Kit)

Free Shipping

Main Highlights

LIGHTWEIGHT, TWO PART POLYURETHANE FOAM: Ideal for adding buoyancy, thermal insulation, soundproofing, and filling gaps or voids; for nonstructural applications only; tested in accordance with U.S. Coast Guard Regulation # 33 CFR 183.114
EASY TO USE: Liquid urethane pour foam has a simple 1:1 mix ratio, expands rapidly & hardens in place in about 5 min. at 70-80°F; to build multiple layers for filling under boat decks, pour expanding foam in separate batches
94% CLOSED CELL FOAM: Perfect for marine applications; resists water absorption and damage from gas, oil or solvents; once cured, foam can be coated with polyester, epoxy or vinyl ester resin; can also be easily cut or carved to shape
IDEAL WORKING TEMPERATURE IS 75-85°F; proper temperature, timing, mixing and venting are critical for proper foam expansion; below 75°F expansion decreases; after mixing, the foam expands rapidly and becomes rigid, so clean the surface in advance and be ready to pour
AVAILABLE IN A 2 QUART KIT AND A 2 GALLON KIT; Yield: 2 Quart Kit 2 cubic ft; 2 Gallon Kit 8 cubic ft; Flotation Range for 2lb foam: 75 lbs per mixed 2 quart kit, and 300 lbs per mixed 2 gallon kit; shelf life is 6 months from date of manufacture

Show Price

9.5

Fiberglass Supply Depot

Fiberglass Supply Depot 2 Lb Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit)

Free Shipping

Main Highlights

Flotation Foam is a polyurethane 2-part foam that, when mixed in equal parts and poured in place this foam will soundproof, insulate, or provide extra buoyancy.
This expandable foam is recommended for void filling in nonstructural applications. It can be poured underneath decks and inside cavities where a lightweight flotation foam is needed to provide buoyancy.
2# Density polyurethane flotation Foam 1 Gallon Kit; Consists of 1/2 gallon of Part A and 1/2 gallon of Part B and produces 5 cubic feet.
Once fully cured this foam can be laminated over with any type of polyester, epoxy or vinyl ester resin without melting.
All expansion rates and times given are temperature critical. Temperatures below 75° F will lower the expansion rate therefore requiring more foam. Ideal working temperature is 75° to 80° F or above. Accurate measuring of these products is extremely critical. Working time before foaming: approx. 45 seconds Time before full expansion: approx. 5 minutes

Show Price

9.2

Generic

Lifeboat Polyurethane Pour Foam 2lb Density 1 Gallon Kit 2-Part Closed Cell Rigid Expanding Foam - Extended Time Formula - For Boat Buoyancy, Flotation, Filling, Deep Pour, Soundproofing, & Insulation

Free Shipping

Main Highlights

LIQUID EXPANDING FOAM to RIGID INSULATION - The ideal foam for marine flotation foam applications, our liquid urethane foam is also great for soundproofing and insulating. Use it to fill dock floats, gaps and cavities in boats and a multitude of other applications.
1-Gallon Kit = 1/2 gallon Part A & 1/2 gallon Part B for a total volume of 1 gallon. This kit has the capacity to expand to a substantial volume of 4 cubic feet. Initially, it exhibits a liquid-like consistency, progressively transitioning into a rapid expansion phase (mix extremely well and fully, scraping the sides of the container and doing so rapidly). It is advised to mix and apply the kit in smaller, measured quantities.To ensure precise control over the expansion process and achieve a more uniform and controlled fill within confined spaces.
EASY TO USE - Great even for novice boat owners! This pourable liquid urethane foam is very easy to work with and expands rapidly. Mix Parts A & B at a 1:1 ratio for best results.
IMPRESSIVE STRENGTH - Urethane is both lightweight and extremely reliable. After curing into its rigid form, our insulating foam boasts a 95 to 98% closed cell structure with a 2lb density
QUICK SETTING - Our expanding foam has a short curing time and minimal shrinkage, leaving your boat ready for use just hours after application. The foam hardens in place within 10 minutes
LONG LASTING RESULTS - Once cured, urethane is unaffected by gasoline, oil, fresh or saltwater, or solvents, making it one of the most dependable and enduring materials for boating needs

Show Price

9.0

TotalBoat

TotalBoat Flotation Foam - 2 Part Expanding Polyurethane Marine Pour Foam For Boat Floatation, Insulation And Soundproofing (2 LB Density, 2 Quart Kit)

Free Shipping

Main Highlights

LIGHTWEIGHT, TWO PART POLYURETHANE FOAM: Ideal for adding buoyancy, thermal insulation, soundproofing, and filling gaps or voids; for nonstructural applications only; tested in accordance with U.S. Coast Guard Regulation # 33 CFR 183.114
EASY TO USE: Liquid urethane pour foam has a simple 1:1 mix ratio, expands rapidly & hardens in place in about 5 min. at 70-80°F; to build multiple layers for filling under boat decks, pour expanding foam in separate batches
94% CLOSED CELL FOAM: Perfect for marine applications; resists water absorption and damage from gas, oil or solvents; once cured, foam can be coated with polyester, epoxy or vinyl ester resin; can also be easily cut or carved to shape
IDEAL WORKING TEMPERATURE IS 75-85°F; proper temperature, timing, mixing and venting are critical for proper foam expansion; below 75°F expansion decreases; after mixing, the foam expands rapidly and becomes rigid, so clean the surface in advance and be ready to pour
AVAILABLE IN A 2 QUART KIT AND A 2 GALLON KIT; Yield: 2 Quart Kit 2 cubic ft; 2 Gallon Kit 8 cubic ft; Flotation Range for 2lb foam: 75 lbs per mixed 2 quart kit, and 300 lbs per mixed 2 gallon kit; shelf life is 6 months from date of manufacture

Show Price

8.8

TotalBoat

TotalBoat 6 Lb Density Expanding Foam Kit, 2 Part Closed Cell Polyurethane Liquid Foam for Boat Flotation, Casting, Carving, Sculpture, Reinforcement and Void Filling (2 Gallon Kit)

Free Shipping

Main Highlights

TWO-PART, MARINE GRADE EXPANDING FOAM cures very hard and rigid, with high compressive strength ideal for a number of marine and residential applications, including structural reinforcement, architectural castings, art projects and flotation
6 POUNDS PER CUBIC FOOT HIGH-DENSITY FORMULA is perfect for casting, carving, sculpture, plug making, sign making, flotation for boats and buoys, floating decoys, part fabrication, replicating wooden parts, rigidifying, structural support and more
FAST-SETTING, CURES TO A 94% CLOSED CELL FOAM, where each cell traps air and prevents liquids such as water, gas, and oil from penetrating; once fully cured, foam is compatible with epoxy, polyester or vinyl ester resins, and can be painted
IDEAL WORKING TEMPERATURE IS 75-85°F. Proper temperature, mixing, timing and venting are critical for proper foam expansion; below 75°F expansion decreases; the foam expands rapidly after mixing, so prep the surface in advance and be ready to pour
AVAILABLE IN A 2 QUART KIT AND A 2 GALLON KIT. Yield: 2-Quart Kit 3/4 cubic ft, 2-Gallon Kit 3 cubic ft; Flotation Range for 6lb foam: 23 lbs per mixed 2 quart kit and 92 lbs per mixed 2 gallon kit

Show Price

8.6

Fiberglass Supply Depot

Fiberglass Supply Depot 2 Lb Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (Quart Kit)

Free Shipping

Main Highlights

Flotation Foam is a polyurethane 2 part foam that, when mixed in equal parts and poured in place this foam will soundproof, insulate, or provide extra buoyancy.
This expandable foam is recommended for void filling in nonstructural applications. It can be poured underneath decks and inside cavities where a lightweight flotation foam is needed to provide buoyancy.
2# Density polyurethane flotation Foam Quart Kit; Consists of 1 pint of Part A and 1 pint of Part B and produces 1.25 cubic feet.
Once fully cured this foam can be laminated over with any type of polyester, epoxy or vinyl ester resin without melting.
All expansion rates and times given are temperature critical. Temperatures below 75° F will lower the expansion rate therefore requiring more foam. Ideal working temperature is 75° to 80° F or above. Accurate measuring of these products is extremely critical. Working time before foaming: approx. 45 seconds Time before full expansion: approx. 5 minutes

Show Price

8.3

Fiberglass Supply Depot

Fiberglass Supply Depot 6 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boats, Dock Flotation, Carving, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit)

Free Shipping

Main Highlights

Flotation Foam is a polyurethane 2-part foam that, when mixed in equal parts and poured in place this foam will soundproof, insulate, or provide extra buoyancy.
6LB. Density polyurethane flotation Foam 1 Gallon Kit; Consists of 1/2 gallon of Part A and 1/2 gallon of Part B and produces 1.5 cubic feet.
Once fully cured this foam can be laminated over with any type of polyester, epoxy or vinyl ester resin without melting.
The 6LB density also works well in floating decoy or taxidermy applications as well as many other sculpting, casting, carving and other filling applications
All expansion rates and times given are temperature critical. Temperatures below 75° F will lower the expansion rate therefore requiring more foam. Ideal working temperature is 75° to 80° F or above. Accurate measuring of these products is extremely critical. Working time before foaming: approx. 45 seconds Time before full expansion: approx. 5 minutes

Show Price

8.1

Generic

Lifeboat Polyurethane Pour Foam 2lb Density 2 Gallon Kit 2-Part Closed Cell Rigid Expanding Foam - Extended Time Formula - For Boat Buoyancy, Flotation, Filling, Deep Pour, Soundproofing, & Insulation

Free Shipping

Main Highlights

LIQUID EXPANDING FOAM to RIGID INSULATION - The ideal foam for marine flotation foam applications, our liquid urethane foam is also great for soundproofing and insulating. Use it to fill dock floats, gaps and cavities in boats and a multitude of other applications.
IMPRESSIVE STRENGTH - Urethane is both lightweight and extremely reliable. After fully curing to its rigid form, our insulating foam boasts a 95 to 98% closed cell structure with a 2lb density. See images for expansion chart.
EASY TO USE - Great for all boaters, novice to expert boat owners! This pourable liquid urethane foam is very easy to work with and expands rapidly. Mix Parts A & B at a 1:1 ratio for best results.
QUICK SETTING - Our expanding foam has a short curing time and minimal shrinkage, leaving your boat ready for use just hours after application. The foam hardens in place within 10 minutes
LONG LASTING RESULTS - Once cured, urethane is unaffected by gasoline, oil, fresh or saltwater, or solvents, making it one of the most dependable and enduring materials for boating needs

Show Price

8.1

Fiberglass Supply Depot

Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit)

Free Shipping

Main Highlights

Flotation Foam is a polyurethane 2-part foam that, when mixed in equal parts and poured in place this foam will soundproof, insulate, or provide extra buoyancy.
4LB. Density polyurethane flotation Foam 1 Gallon Kit; Consists of 1/2 gallon of Part A and 1/2 gallon of Part B and produces 2 cubic feet.
Once fully cured this foam can be laminated over with any type of polyester, epoxy or vinyl ester resin without melting.
The 4LB density also works well in floating decoy or taxidermy applications as well as many other sculpting, casting, carving and other filling applications
All expansion rates and times given are temperature critical. Temperatures below 75° F will lower the expansion rate therefore requiring more foam. Ideal working temperature is 75° to 80° F or above. Accurate measuring of these products is extremely critical. Working time before foaming: approx. 45 seconds Time before full expansion: approx. 5 minutes

Show Price

Our Best Overall Choice

Best Choice

9.7

Oycevila

2 Quart Kit Marine Flotation Foam with Gloves, 2 Lb Density Polyurethane Expanding Foam for Fence Gap Filling, Reinforcement, Closed Cell Pourable Polyurethane for Boat Flotation, Insulation

Free Shipping

Editor's bottom line:

“This is the best one we tested. In terms of quality, brand and price, we couldn't ask for more.”

Main Highlights

EXCELLENT FLOTATION SUPPORT: Expanding foam for posts when cured, fence post foam creates a strong, closed-cell structure that traps air, contributing to the flotation capabilities of marine vessels and structures. This feature is crucial for ensuring that boats and marine structures remain afloat, making it a popular choice for manufacturing and repairing sailboats, kayaks, canoes, and other watercraft.
STRENGTH AND DURABILITY: Upon mixing the two components, the expanding foam expands significantly, allowing it to fill voids and cavities effectively. T Despite its lightweight nature, polyurethane pour foam is remarkably strong and capable of withstanding harsh marine conditions, including impacts and constant exposure to saltwater.
INSULATION PROPERTIES: The flotation foam's insulating properties help maintain temperature stability within boats, making fence post foam ideal for insulating fish boxes, bait wells, and marine refrigeration units. This feature enhances the comfort and functionality of marine vessels, especially in extreme weather conditions.
VERSATILITY IN APPLICATION: This liquid foam can be used in a variety of marine applications, not only for buoyancy but also for insulation, soundproofing, and vibration dampening. Marine polyurethane expanding foam is easy to use and ability to conform to any shape or space make it a versatile choice for both construction and repair work in the marine industry.
PROFESSIONAL TECHNICAL: 1:1 mix and stir evenly, the working time before foaming is about 45 seconds. Apply in layers for thicker applications, allowing each layer to cure before adding the next. Make sure to cover the entire surface evenly.

Show Price

Deals are Live

Special Amazon deal ends in: