|Topic Review (Newest First)|
|08-04-2008 04:40 PM|
|Teirst||thanks a lot captain gary. i had no idea that the ohms thing with the motor was a big deal at all. i will speak with a marine mechanic in the area (new england area seems to have a very large boating community) about addressing the issue. also thank you for bringing up the insurance costs that is another thing that i had no idea of. i am still a little concerned about the moisture content of the hull. a little bit of backround on myself i have always been a do-it-yourself kind of guy and have a lot of experience with wood (cabinet making/construction) and motors (cars/rebuilding/replacing/even worked as a mechanic) but have no idea when it comes to fiberglass and the whole inspecting a boat thing i am very new to.|
|08-04-2008 04:24 PM|
If the engine was supposedly bonded and has 600K ohms of resistance to the ground lead on the shore power plug, then something is very much wrong. If you decide to go ahead with this boat, I'd suggest you get a galvanic isolator and put it just inside the boat past the shore power line, then run a brand new ground lead from the AC ground (green wire!) to the engine block or the 'star' point of the bonding system. Then I'd poke around with a digital voltmeter and see what kind of resistances you find between the engine block and the battery negative terminals. It should read very near zero. (Just make sure to pick a spot with no paint on the block!)
Since it's a gas engine, and gasoline has some nasty habits (like happily exploding in the presence of an arc or spark), you need to make sure that the Fuel fill fitting is electrically attached to the gas tank, and the gas tank is attached to the engine, and the engine is attached to a grounding plate that is in good contact with the ocean. The whole idea is to keep everything at the same electrical potential. I know this sounds crazy, but when you're filling up the gas tank, especially during the summer when it's reasonably dry, the gasoline rushing down the rubber hose can build a static charge. Then you move the fuel nozzle a bit, provide a tiny ground and you get an arc--boom! It happened to an older Tollycraft sport fisher down in Miami a couple of years ago, and the resultant explosion and fire burned about a quarter of the marina down, and a lot of adjacent boats!
Another thing to consider, if you're not too far along: check with your insurance broker. Ask him the difference in the cost between insuring a gas vs. a diesel boat. You'll probably be shocked.
BTW, I'm impressed that your surveyor checked things with a meter. Sounds like you got a good survey. Ditto on the moisture numbers.
|08-04-2008 10:53 AM|
Was wondering if I could get some interpretation. I got a survey for a boat that I have been interested in but have been a little unsure as to what all the numbers and things meant. I believe that the boat would be a good purchase but then who shoots down a second opinion. Let me know what types of other information you would like but here are what I think are the big ones. let me know what you think about it
1969 Columbia 36í sloop
Ge aquant moisture meter scale of 1-999
Hull below water line (less than 247)
Hull above water line (88-116)
Hull surface: observed minor compression dimples, abrasions, and gel-coat voids of no structural consequence (cosmetic only) both sides amidships well above waterline
Hull to deck join: shoe box style, aft sections of the coaming have sustained damage on starboard side and appeared to have been partially repaired. I recommend thorough repair.
Engine: atomic 4. engine was bonded but has 608k ohms resistance to shore power ground receptacle and fuel tank. Resistance from fuel tank to engine was 5.5k ohms. And fuel fill was 750k ohms to engine block as well
thanks for all your help!