Boat Search: Hulls and Bulkheads that don’t sink your boat!

March 19, 2020 Peter Grande 0 Comments

My Search for the best sailboat for me, includes a lot of looking, feeling, hull pounding and pulling of lines!  

These are the things we boat shoppers have to do every time we get in our car, to drive to a new showing.  Boats are a lot of work.  If you come across the best listing, the perfect internet ad, showing you the boat of your dreams, be prepared, it may just be a nightmare floating, or held up by stilts.


My search has taught me a lesson.  Every boat, big or small, needs to have a survey done.  I know this is a fact, but I realize that looking at so many boats may be just too expensive to have a survey done on each one.  I’ve decided to save my money, and start doing mini surveys each time I look at a boat.  

Of course, I’ve looked at sailboats in the water, on the hard, at the boat shows and in just about every condition.  There are some things I believe you need to be aware of, so that you can make an educated determination on purchase your boat the way that I’m doing this.  

I’ve decided to educate myself to do the best inspection I can do, and invest in a full survey once I decide to put a deposit down on my news vessel.

Part 1 - Hull & Bulkhead Inspection

The hull, in my opinion, is probably the most important part of the boat, at least in my mind.  The hull is what is going to keep you afloat, and if you are like me, I’m looking at boat Monohull and catamarans.  I’m not fussy!  More about that in an upcoming article.

Old boats can have a many issues, so, if you’re looking at older, specifically, fiberglass hull boats, you should consider the shape of the hull.  You should understand the construction of a boat that you are looking at.

Hull Construction

The hull of the boat, is obviously, the shell of the boat below the deck line.  Fiberglass hulls are made of many layers of resin and fiberglass types, and built to take a good beating.  To support the hull shape and to stiffen the hull, and support the boat as a whole, the inside of the boat is made up of several, or many bulkheads.  

Bulkheads are vertical walls that are mostly perpendicular to the hull, and bonded to the hull on the inside. 

Some bulkheads are built to go from one side of the boat to the other side of the boat, port and starboard.  Some bulkheads are bonded (tabbed) to the hull along the hull in sections, and may only be a couple of feet in length, but almost always as high as the cabin they are installed in.  Bulkheads are the 2×4 construction of a fiberglass boat.  They are necessary to provide ample structure and strength to the hull itself.

So, lets talk about what we want to see in the hull inspection, with regards to the bulkheads.  On the outside of the boat, there is a curved shape to the hull on both sides.  Curving both horizontal and vertical.  If we stand at the stern of the boat (the back), and look towards the bow, (the front of the boat), we should see a nice evenly curved shape to the hull, from stern to bow, from the deck line to the keel, (the bottom of the hull).

A Good Hull

On a good hull, in relative good shape, you should be able to look down the sides of the hull, and see no warping or mis-shape to the hull.  The image is not the best, but represents what a hull in good shape should look like.

The lines on the hull should be straight and even, showing no distortion to the path of the hull lines.

A Bad Hull

On the contrary, a bad or warped hull will show uneven lines, and hull deformation.  Looking along the lines, as in this example shows that the warping runs vertical (up and down).  This sort of damage to the boat can be problematic to a purchaser.

Some people tent to think that these things are minor, but the reasons for this type of warping can be an expensive repair.

What if the hull is warped?

There are many reasons the hull of a fiberglass boat can warp.  This can lead to much larger problems with the boat if you are not aware of why this happened, if the damage was repaired, but improperly, or if it is going to lead to a structural issue.

Lets take a look at several reasons for this type of hull damage, and what some experts would say, you should walk away!

Untabbed Bulkheads

As I mentioned earlier, bulkheads support the hull from the inside of the boat.  These Bulkheads are the strength to the hull itself in most cases.  If a bulkhead is damaged or untabbed, this can lead to a weakness in the hull, and cause warping.

In most cases, the pressure of the water pounding against the hull, may be a reason that the bulkhead has broken away from the hull itself.  The bulkhead may have become untabbed, meaning that the fiberglass/resin that holds the bulkhead to the hull has broken and they are no longer attached to each other.  In some cases, this is a repair that can be done, but, you would have to look at the inside structure of the boat to determine what kind of access you have or a shipyard has to get this fixed.  Internal panelling or structures may have to be removed to perform the repair.

If most of the interior structure, such as seating, walls, panels, cabinets need to be removed to fix the tabbing, then you can expect a very large bill to perform this repair.

Additionally, if the bulkhead is cracked or water damaged, it may have to be replaced.  This could result in the same problem with removal of some or all the interior of the boats seating, cabinets, etc.  Again, this is an expensive repair.

If you are considering purchasing a boat as a project, and intended to rebuild the entire boats interior structure, then getting to, replacing or repairing the bulkheads may be within your scope of work.  This, however, is not often the case.

Untabbed bulkheads can lead to other damage to the hull.  As the hull twists, it can actually cause damage such as cracking of the gelcoat, to the fiberglass structure, and even lead to more significant problems causing such things as large cracks nere sea-cocks or holes in the hull.

So, yo can see, bulkheads are important to the structure of the boat’s hull, and you should check them carefully.

Boats stored on Cradles

There are typically two reasons boards are stored on the hard (land stored) in a cradle system.  First, like my first boat, if you live in a cold climate, the boat has to be taken out of the water in the winter time, so that snow and ice do not cause damage to the hull.

Second, is to store the boat on the hard, to do service work on the boat.  This is more common for temporary repairs.  It is much easier to do work on the boat, especially if it is below the water line, to pull the boat out of the water, store it, and work on dry land.

However, if the boat yard you are using, does not put the boat onto the cradle correctly, it can cause warping or damage to the hull.  Here is why…

Boats need to be placed into a cradle system, with the palm of the stand, (the part that touches the boat), located at a strong bulkhead location.  Some boats have these locations marked at the deck joint line, others are noted by examining the interior of the boat to determine where the bulkheads are.

If not placed on the cradle properly, the weight of the boat will put too much pressure on the cradle, and the palms of the cradle stand will damage the hull, warping it or causing surface cracking.  Most of the time, if the boat is stored for only a short period of time, 30 days or less, damage is not caused.  However, if you are buying a boat that has been in its stand for a long time, you need to check to see if the cradle is supporting the hull at the bulkheads, otherwise, you could expect damage.

On a separate note, I just want to mention that my boat received some keel damage after being hauled out once.  The yard placed the boat on the cradle, and typically, blocks of wood are placed under the keel between the bottom of the keel and the ground.  This is to help support the boat from the heaviest and deepest part of the boat.  The boat was placed in the cradle incorrectly, and cracked the keel.  It wasn’t significant damage, but did require about a weeks worth of grinding, laying up fiberglass, and re-painting.

Once the hull gets warped from this poor storage method, you may not be able to fix it.  Thus, leaving the hull of the boat permanently warped or damaged.

Again, this can be expensive to repair, especially of the boat has been sitting for a long time.  Boats can sit in shipyards for years sometimes, as owners do not want them in the water, if they intend not to use them, or if their lifestyles change.

Haulout Straps

Having your boat hauled out of the water is part of both having a survey, or getting it on the hard for either storage or shipyard work.  When hauling out, it is important for the shipyard to know where your bulkheads are located along the sides of the hull.  The placement of the strap can cause damage if placed incorrectly.  This is very rare, but it can happen.

I’ve seen very heavy boats pulled out of the water on straps, and you can see the flex in the hull.  It is going to happen, but placing the straps correctly can save a boat from any potential damage.  

If you own a boat, or are planning to purchase a boat, I would recommend that you be around the shipyard the day that your boat is being hauled out or put back in the water.  

Leave a Reply:

Your email address will not be published. Required fields are marked *