How to look after your boat transom

The structural integrity of your boat's transom is hugely important, epecially as it needs to hold the weight of an outboard that can weigh hundreds of kgs! A transom that’s in poor condition can be dangerous and can put yours and your crew’s life at risk. Read on to find out how to inspect your boat's transom and protect it from damage. 
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What is a transom on a boat

​Your boat’s transom is the flat surface at the back of the boat that your outboard attaches to. Whereas the ‘stern’ refers to the back of the boat, the transom is specifically the back panel that the outboard motor is attached to. 

It’s a good idea to check it regularly for cracks or wear and tear. And if you’re inspecting a boat to buy, a thorough pre purchase check of the transom is an important step. 

How to check your boat's transom

Aluminium boats: 
Check for cracksm especially around the weld marks, also discolouration around bolts can indicate water ingestion and a possible lack of sealant during motor install. Older ali boats have a ply wood backing pate to support the outboard, this is a common area for corrosion to hide causing the bolt holes to get out of round.

Fibreglass boats: 
Firstly, check the transom for cracks. On a fibreglass boat check if the cracks are superficial (i.e. just on the gel coat) or if they go deeper than that. When they go deeper there's the potential for delamination. Delamination occurs when the layers of fiberglass cloth and resin detach from each other or from the core that lies between them.
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Also check for softness or sponginess as this can indicate the presence of water ingestion and potentially rot. Rust stains around the bottom bolts are a good indication of water entry causing the transom to weaken.
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What causes a transom to degrade?

It’s fair to say that wear and tear over time and the stress on the transom are the main causes of your transom degrading, but the following issues can drastically reduce the lifespan of your transom.  

1. An outboard that's too heavy for the boat. Every boat has a recommended hull weighting, which should be adhered to.
2. The outboard was not rigged up and protected properly during the install, allowing water to enter and degrade the transom (on fibreglass and wooden boats)
3. The boat is trailered long distances without a transom saver, especially on dirt roads which causes the engine to bounce and cause stress on the transom. ​

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Repowering

When you repower your boat with a new motor, it’s a great time to inspect the transom. When the old motor comes off the Marine Technician will inspect your transom to see if it’s fit and ready for your new engine. This is the time that they’ll discover cracks, weaknesses and any sponginess. If the transom has suffered water ingestion they can determine the cause of this – i.e. was it through the bolt holes, or cracks. 
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Once they’ve inspected the transom they can work out if the transom is fit for the new engine, needs reinforcement to strengthen it, or major repair work. 
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How to reinforce your boat's transom

On an alloy transom, clean up the area, add an aluminium plate to support and strengthen the area. We work with specialist fabricators who shape and mould alloy plates that can be fitted to the transom to strengthen it. 

Reinforced alloy transom

On a fibreglass transom any reinforcement work depends on the moisture level of the transom as that will dictate whether it’s a repair or complete replacement. If delamination is present, exposing the inner layer, it’s important to dry out the area before packing with epoxy, then applying a fibreglass and resin. 

Protect your transom for years of trouble-free boating

​Invest in a transom saver:
We’re often asked by boaties if they need a transom saver or outboard motor support when trailering their boat. We always recommend investing in one. For a relatively inexpensive piece of equipment, it can save you thousands - prolonging the life of your transom and helping you avoid costly repairs.

Check your transom regularly:
As mentioned earlier part of your regular maintenance should be checking your transom for cracks, discolouration, delamination and sponginess.  
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If you’re unsure about the state of your transom, get a professional to check it over. And if you’re looking to buy, a pre-purchase inspection that includes a hull inspection is a good idea.