looking to buy hydrodyne 18 ft

Alright thank you for the advice!

 

I would not drill a hole through the hull in a Dyne. The 70's dynes with the raised floor have end grain balsa and can have pockets of water or a local void. How many holes do you want to drill to check the entire core?

A 69 Dyne has longitudinal grain balsa and water can travel through the core soaking the whole thing. It should be tap tested inside and out because there are two layers of core.

Learn to do a tap test, and check the entire hull. If the floor has soft spots, the transom is suspect. The water can enter the transom through the engine mount bolt holes.

sorry tj, jim

 

No problem Jim - I am always open to a better way.

 

After thinking this about this I am in error. I am in the middle of a major restoration and I forgot the fact that there is a floor over the core. I would never advocate drilling a hole in the bottom of a hull to check. If there is an area by the transom where the floor ends and you could drill a test hole into the core my idea would work. I think removing a lower motor mount bolt would allow a good inspection of the transom. If that is bad you dont want to buy that boat. If that is good use Jim's method to check the rest. I do not know how to tap-check but I am sure Jim will reply and tell me and you how to do it.

 

It is simple, just tap on the hull in a way that will not damage the finish. I use the butt end of a wooden hammer handle. If there is a void or water, the tap will sound dead or dull. It is not difficult.

The 60's boats do not have a flat floor above the hull. The 70's boat do. The 60's boats have a two layer balsa core where the grain runs longitudinally and water can travel through it. They are much more apt to have a soaked core. If an 18 foot Dyne has a hull identification number stamped in the transom, it should have the flat floor and end grain core.

The 70's boats with the flat floor have a core where the grain runs vertically which is called end grain. It is fairly rare to see a soaked core in these boats, but it has happened as in TJ's boat.

Rotting floors and transoms will happen, but many boats have lasted 30 years before repairs were necessary. It all depends on how they were cared for. Most experienced Dyners try to keep the boats dry. TJ's approach is to eliminate the wood. He is doing the work himself. If you were to hire that work done, it would be cheaper to buy a new boat.

Many nice boats have had a floor and transom job.

jim

 

Actually Jim it appeared that the bottom core had the grain running longitudinally in my 72 and the core over that one too. The second core was much heavier than the bottom one and appeared to be something other than balsa but it was too rotten to make a positive ID.

 

Does it have a hull identification number stamped on the outside of the transom, on the right side, and if so,what are the last two numbers? And, did it have a raised floor with stringers"

jim

 

Looks like from the pics that his flat floor was added by someone. I've rebuilt both but like the older setup better. From what I remember 72 was the year they made the change.

 

This is an interesting situation. I always thought that if it had a HIN stamped into the transom it had the raised floor and end grain. We shall see.

jim

 

There is no HIN. Since mine is a 72 maybe it was built the old way and later 72's were built the new way.