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The Core... What is it, and where is it at?

So, you just bought a Hydrostream and now you are told that the core needs to or should be replaced but you're not exactly sure what the "core" is.

The core is a Balsa wood layer that is under the floor of the boat, and is bonded to the hull (bottom) of the boat and covered by a layer of fiberglass that provides the hull with all of its strength and structure while keeping it extremely light weight. Without it the hull will be very flimsy and make for a poor handling boat, and very prone to delamination which can lead to serious injuries!

The problem with Hydrostreams and the ever rotten core is, back when these were being made, they were making so many of them that they were making them as quickly as possible so quality control wasn't always the greatest when it came to the structural build quality. Also, Howard Pipkorn wasn't expecting them to be around 30 to 40 plus years later. What happens is moisture gets in under the poorly sealed fiberglass and when wood is introduced to moisture, it will rot and in some cases, disappear all together. Some say a tap test on the hull is a good way to check for a rotten core but sadly, it is not. I have heard them sound nice and solid and they turn out to be the top half of the core is soaking wet.

It should also be noted that while the core is a big issue on these, the rest of the main components of the boat, the stringers and the transom, also are a big problem area with these and will usually be just as water logged as the core and will also need to be replaced.

Here are some pictures of where the core is located. (NOTE: On desktop devices, you can click the images to enlarge them)

In this picture you can see here where the floor is, and the stringers, and then the core. The core is outside of the stringers and also located down the center of the pad area.


The next two pictures show the wet rotten core.



Here again is the core and also the foam float boxes. These foam float boxes suffer from the same issues as the core and are often full of water therefor becoming very heavy, and letting water even further into the boat.

Also should be noted, on some hulls, such as the Viper and Vector, there is core all the way up to the outside edge of the hull, under the float boxes, so the float boxes will need to be removed to replace all of the core. The Vking and Vultures are not like this though and they rely on an outer stringer for the hull support.


Here is a Viper with the classic rotten Hydrostream core.


This a Hydrostream Viper with all of the core removed and ready for it to be replaced with brand new core. Once the new core is down and sealed up properly, the boat will easily last another 40+ years, if not longer.


Here is a great example of a VKing with, new core, new stringers, and new transom.


Just a side note, as seen in these pictures here with the deck removed from the hull, it is not necessary to split the hull to replace the inner structure of a Hydrostream. It does make for working easier but certainly not required.

A HUGE thank you to Josh Brown (spongebob440) for sending me the cut away pictures of the Hydrostream VKing to use in this. The boat delaminated due to a rotten core and was junk so they cut it half and sent it off to the scrap yard and Josh got a few pictures before they threw it out. Also, thank you to Adam De Kuyper (AdamDK) for the pictures of the Viper and Tony Nelson (tnelson77) for the picture of the WIP VKing.

If you would like to discuss any of this you can do so by clicking here: https://www.hydrostreamforums.com/viewtopic.php?f=9&t=3619

Remember, as the saying goes, there are only two types of Hydrostreams, ones that need the core replaced, and ones that have had the core replaced. No matter how much someone tries to tell you an original Hydrostream is solid, 99.5% of the time, its wet and rotten. No getting around it.

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