The boat transom is one of the most important parts of a boat. It is a structural part that holds everything else together, and without it, the boat is not usable.

The first thing that needs to be done is treat the rotted areas with CPES ™. This is best done after the interior wood is dry but before the new core is put in. To learn more about Boat Transom Repair read the article below.

The boat transom is one of the most important parts of a vessel. It supports and holds a lot of weight, handles the thrust and force of engine power, and provides water access to your boat. A rotten transom can be dangerous, as it can deform and allow water to enter the boat. It is best to be proactive and reinforce a rotten boat transom before it becomes too damaged to fix.

Every boat has its own set of challenges when it comes to gaining access to the transom and making repairs or replacing parts. This is especially true of older boats. The aft end of the transom is usually very tight and difficult to gain access to. This is where most rot will occur and also where the most damage can be done to the transom structure.

There are some ways around this, but it takes time to find the right one. It is a good idea to have a professional assess the condition of your boat’s transom and make any necessary repairs. A qualified shipwright, boat builder, or marine mechanic can help with this and ensure a quality job that is safe.

It is also important to have the boat well supported when removing a portion of the hull or transom. This can be achieved by using a bunk trailer with additional blocks under the keel and transom. This will protect the hull from becoming deformed and “oil canned” when removing the transom or stringers.

Often, the boat transom is built with fiberglass on both sides of the plywood core. This is not uncommon, but it makes the process of removing and replacing it very complicated.

The transom is designed to be very durable in order to absorb the engine force on a powerboat and transmit that force to the greater hull structure. Many people even put their name on the transom of their boat because it is so durable and functional. It is a very important part of any vessel, and it should be assessed regularly to ensure it continues to function correctly for multiple uses.

Removal of Old Plywood

It seems obvious that the first step in a transom repair job is to gain access to the old plywood. That way, bad wood can be removed, and what remains can be dried out. Dry wood is far more likely to take up epoxy and other marine adhesives. This is especially true of rotted and compromised exterior-grade plywood. If the wood is encapsulated in West System Epoxy, it can be saved; it will just have to be cut away from where it is stuck down to the fiberglass (or other material) and cleaned before it can be reused.

In some cases, a simple cleaning with CPES (TM) can restore the deteriorated, rotting wood to its former strength and stiffness. However, that process requires drilling access holes through the top of the stringer 5 to 7 inches apart, allowing the interior wood to dry (or blow-dry), and treating with a CPES injection before filling all voids with Layup & Laminating Resin ™.

Most powerboats have a wooden mast step, and these steps are prone to rot and deterioration. They are relatively easy to rebuild using a combination of CPES (TM) and Layup and Laminating Resin (TM).

When considering any boat transom repair, it is important to have a qualified shipwright or boat builder perform the work. Unqualified tradesmen will only make the problem worse and could cost you in damage claims down the road.

Before beginning any demolition, it is best to make a template of the inside of the transom, including the plywood thickness and stringer location. That will help in drawing the wide pieces that will make up the new inside transom skin.

A reputable fiberglass shop should have these templates and can do this for you for a very reasonable price. Once the old plywood and bonding putty are removed, lightly sand the old interior transom skin and then apply a liberal amount of Layup & Laminating Resin (TM) to a piece of cheap plywood or cardboard. Let this dry, and then use it as a template to mark the width of the wide fiberglass pieces that will form the new inside transom skin.

Core Replacement

The transom’s plywood core is a very important structural component. It is subjected to a lot of pressure and stress from the outboard motor. If it becomes damaged, the entire boat’s structure could fail. To ensure the integrity of the boat, it is a good idea to replace the damaged portion of the core. The best way to replace the core is to scarf in new plywood sections. This is the method most commonly used by professional boat builders and shipwrights to repair rotted transoms. The procedure is explained in Section 6.3.2 of the West System Wooden Boat Restoration and Repair Manual (free download).

When replacing the damaged portion of the core, make sure that the new piece fits and is properly bonded to the old transom skin. A good practice is to cut the new plywood piece 1/8 inch (3 mm) larger than the size of the existing skin. This will allow for a proper fit and will also reduce the amount of epoxy required to bond the new section.

Using the wrong thickness of plywood for this job can cause major problems. It is a good idea to use the same type of plywood as the original and to get it from the same source if possible. It is also a good idea to match the wood grain as closely as possible with the existing transom.

Once the old plywood is removed, the core should be sanded to remove rough areas and prepare it for new fiberglass. It is a good idea to also grind down any remaining bonding putty in the corners of the transom.

If the old transom skin is intact and there are no signs of rot, it may be possible to skip the core replacement. However, it is a good idea to have the transom professionally assessed and repaired by a qualified boat builder or shipwright who can guarantee their work in the event of a catastrophic failure.

A marine surveyor can provide an invaluable assessment of the condition of your transom and other parts of the vessel. It is also a good idea to pull and re-seal all through-hull fittings, engine bolts, and hardware fasteners on a regular basis. Moisture from these fittings can penetrate the transom skin, causing delamination and rot.

Layup and Laminating Resin

When the transom is repaired, it is important that it be done with epoxy resin. There are a number of reasons for this: 1) It is easier to use, 2) It cures more clearly, and 3) It will make the new part stronger and less brittle than polyester resins. Epoxy also holds up well under vibration, allowing it to carry loads.

It is also best to put the new laminate on a good, solid base. This will improve the strength of the repair and allow it to withstand the forces on the top of the transom.

A good base is a 4″ or 6″-thick piece of plywood or fiberglass mat. This is bonded to the old outside skin of the transom with an appropriate adhesive, such as epoxy bonding paste or epoxy primer. A layer of fiberglass cloth is then laid over the base, and a second coat of resin is applied to it. A final coat of resin is then applied and left to cure.

After the epoxy resin is cured, it is important to remove all excess and any loose fibers from the layup surface with plastic wedges and a hammer. This will also give you the opportunity to trim off any stray fibers that might impede the form, fit, or finish of the carbon part.

It is important that a proper epoxy laminating schedule be followed to ensure a strong, long-lasting repair. It is also important to avoid using too much resin, as excessive resin can decrease the strength and stiffness of the part.

A proper laminate is a combination of both woven and unidirectional glass fabrics with a high proportion of chopped strand mat (CSM). The amount of CSM used determines the strength and stiffness of the part. The type of resin used depends on the project, with polyesters being most common for boat construction. However, epoxy resins are also used for their high strength, abrasion resistance, and moisture resistance. Epoxy resins are more expensive than polyesters but provide superior tensile strength. They are suitable for a wide variety of wet layup applications, such as laminating and repairs on both marine and industrial parts and structures.

Debbie Dean