Jim, This boat is haunting me. I was sure I didn't want it....but it stays in my brain. I am familiar with Hydrostreams which were notorious for poorly sealed core from the factory. Everyone who checked their core found rot. I got a real bad attitude about balsa core from that experience. Can you tell me why you think the core may be intact? Bernie
The 70's Dynes used end grain balsa which was well sealed. If water does get in, it can't go anywhere because the grain is vertical. The 60's Dynes used planks that ran longitudinally. If water gets in it can travel along the filaments and soak the whole bottom. I can't recall a 70's dyne that was soaked. There probably is one somewhere. It is easy to tap on the bottom and the transom and listen for dead spots. I am familiar with Hydrostreams, and that is a different story. They are prone to soggy bottoms. jim
The Hydrostreams were end grain blocks too. The 70's 'Dynes must have had a much better crew laying up the 'glass than Hydrostream did. The top cover over the balsa was done with a chopper gun and while I was on the "Scream and Fly" website there were a lot of hopeful buyers getting them and hoping (like I did) they THEY would be the lucky one who got a good core. NOBODY got one, even an unrigged original that had lived in a warehouse for almost all its life. It was rotten from the dealers lot. You are encouraging me though...the issue with the 'streams was that everybody wanted to go 80 mph and at that speed, delamination may well kill you. Even if a 'dyne delammed it would likely be a bad day at the lake and not a bad day at the morgue. Now I need to decide if I want to drive 10 hrs round trip and spend a day and $175 to find out for sure. (Pretty sure I do!) Thanks, Bernie PS, I tried the 'tap and listen' method and I couldn't tell...if I had tapped a LOT of boats with good and bad core I might have learned....I know that is what professional marine surveyors do along with using a 'moisture meter' but I can't trust one without drilling test holes.
I am a long time member of scream and fly although I have been inactive for years. I have driven streams with soft bottoms and good bottoms. The difference in the tapping sound is quite clear. Wet is a dull thud, and dry is a sharp sound. If the boat has been left outside with water in it, then it is suspect. The pieces of balsa are dipped in resin as they are installed (I think epoxy). I had a Mirage Ski Racer with a modified 2.5 260 while I was active on S&F. jim
That would be the way to install, time consuming and expensive though. I expect a high end tournament boat likely cost a LOT more than a fast runabout back then. I'll try the tapping again if I go and get it, but if it comes home with me and I find wet balsa I'll probably rebuild it anyway....I'm a sucker for a cool old classic boat. I grew up in FL. and while we were skiing behind a Glastron GT160 with a 100 OMC I saw LOTS of cool boats that I really wanted but couldn't afford. Now they are old derelicts in most cases and so far I have revived three of them, but none were as big a project as this. I would imagine your Mirage was running near 100 mph...my old stream was a handful at 70....I never really got the hang of a Vpad boat. Thanks, Bernie
Further to Jim’s earlier email where he said "The 70's Dynes used end grain balsa which was well sealed. If water does get in, it can't go anywhere because the grain is vertical." and "I can't recall a 70's dyne that was soaked. There probably is one somewhere. It is easy to tap on the bottom and the transom and listen for dead spots" Sadly, I have 2 of them. I've taken on the hobby of restoring the core on the newer of the two - not sure the extent of the core damage in number one, but in number 2 it was extensive. While as Jim mentions, you can tap on it and see what kind of sound you get, solid thud, or not so solid thump. In my case, I did it from the inside with the stringer floor removed. Tapping revealed about a 2 square foot zone that was definitely bad. Cutting back the top sheet of glass revealed way more. In fact it took 4 sheets of 2' by 4' replacement core to repair the bad portions, although some of it was over cut out to have consistent lines. Also, the hull must be very well supported underneath if you're removing large sections of damaged core, otherwise you could get undesirable flex in the hull from your bunks after removing the old core which you will get formed into your repair if not supported. I first repaired as much as I could with the top on, glassed it all back down, and then popped the top off to fix the areas covered by the top in the back and front. "Popped the top off" is a bit of a stretch. It was really hard getting the top off given the rivets, and glassing, and the fact a previous owner had replace the rotten sandwiched plywood with a the sticky calking. But it’s done. If anyone’s wondering, yes the transom is shot too. I will post my repair with pics as a separate thread when I have time.
I plan on making a few more test holes but the Hydrostream I re-cored had nothing but brown dirt under the top fiberglass layer where the balsa should have been. It was rotten from stem to stern. I am happy to find any wood not rotten in the 'dyne. Good luck with yours. Bernie
