hull integrity question

[vinnie1234]

Hi jbcurt. What places are customary to measure / monitor on small boats? If the hull flex is severe enough to cause a major failure then in my logic I can see only 2 places one needs to measure on this boat. Across the beam midships, and at the engine where my rotten stringers are. Changes at the beam will occur as a result of any type of hull flex. I see merit in measuring deflection at the engine because the boat has 140hp and rotten stringers. I was just reading about an hour ago - Googled hull flex measure or something and I discovered that they use 4 gages typically on a freighter, all on deck to measure hull flex. My boat is too small for that type of system to be effective, and I have read more than a few posts about sag in the aisle on a bowrider, so I put 2+2 together and thusly devised my theory. The main reason I explain my thinking here is so that someone can poke a hole in it for me. Shoot!

 

[jigngrub]

:boink:You're waaaay over thinking this, it's an old rotten boat and it just needs fixin'.

You've probably only got a couple of more good weeks of boating season left anyway before the Bay freezes over again and all the Canucks go out on the ice and start beating on it with their hockey sticks trying to knock a hole in it so they can catch a Pickeral to go with their Kraft Dinner.

Remember the last time you were out, all big and brave fishtailing the boat down the backside of waves and stuff? If she didn't break up on you then, she probably isn't going to break up any time real soon either... maybe.

I've always been of the mind that if you can't go boating, the next best thing is working on a boat... catch my drift?

 

[vinnie1234]

Yeah, you have a good point there. You know what they say - people fear the unknown. My lack of experience with this has got me thinking about the worst. I gave the boat a pretty good pounding the other night and it's fine still. so I will stay home unless it's calm and maybe visit the Inland lakes a little more often this year. I guess I will work on my reno plans now!

 

[vinnie1234]

Short update: Before attempting to measure the boat I thought that perhaps I might call the manufacturer and see if someone there might have an idea as to what behaviour would be normal for the hull. In the discussion I told him the conditions of my last ride out and he said the same thing that jigngrub did (basically). He said "if you are doing those kinds of speeds in that high of waves - I'd say the boat is pretty solid".
Now this doesn't mean that I'm going to go right out and see how much air I can get, but I think I feel safe enough using the boat for the remainder of the season.
I will keep my eyes on the engine mount bolts, however when I put my front engine mount back in, the bolts took about 180ft lbs of torque, so the stringer can't be that soft.

Gentlemen, I thank you all for your time and helpful advice! I will be sure and post to the restorations forum in the winter, in between bashing the ice with my hockey stick, and stuffing my face with KD.

 

[jigngrub]

in between bashing the ice with my hockey stick, and stuffing my face with KD.

I just say that kind of stuff because I'm Canadian by marriage

My wife was working in Windsor when I met her and her mother and sister live in Port Perry just below Lake Scugog. Her brother live in Cold Lake Alberta and her son is in the Canadian navy in Halifax.

So I have to stay polished up on my Canadian lingo.


Glad you got some of your confidence back with your boat, and I know you'll be cautious and careful the rest of the season.

I'll be looking forward to your tear down and resto this winter, it sounds like you might be a little OCD like me so it should be a good build.

 

[vinnie1234]

Hey Jig, no offense taken. People like to make fun of us canucks, but we don't mind. I thought your comments were pretty funny. I will confess that I've never had a feed of pickerel and KD, perhaps I will try it and see if I feel more Canadian?
As for the build, I hope that I am able to do a top job on it. There is certainly enough knowledge and helpful people on this forum to give me the help that I need.

I guess I had better log off and grab a double-double before I start my day eh?

 

[Scott Danforth]

Jumping in just for the curiosity and because I have $0.02

Just a few thoughts

putting a dial indicator on the hull will do nothing except show you the hull flexes (with or without stringer rot). All structures flex with load, or they break.

thumping on the hull proves nothing. I have thumped on hulls with rubber mallets, had people say the hull and structure is perfect, then had the surveyor pull out his moisture meter and prove everyone wrong.

Todays surveyors also use thermal imaging (rot shows up as a different color)

I have drilled 1 or 2 test holes to show good wood, only to have a screw come out 6" away and have water running out the hole. More test holes around the screw and.....new stringers and transom.

Every boat that I have seen with a soft spot in the floor ends up as either a total resto project, or gets scrapped when the realization that the work outweighs the benefits of the hull. boats rot from the keel up

manufacturers used wood for many reasons - the material is plentiful, inexpensive, strong, easy to work with, will last the lifetime of the boat, and is non-toxic. the lifetime of a boat is generally 5-10 years, just like cars. if cared for they can last 5-10 decades without issue. (as a comparison, car manufacturers use low grade carbon steel for the structure for the same reason that boat manufacturers use wood)

Todays boats have engineered stingers or stringer tubs. the hulls are put together as multiple molded sections that are then securely glued to the outer hull. my last visit to Ski Nautique I estimated 5 gallons of adhesive being used in a 21' hull.

comparing handling charactoristics of a boat over the phone with someone who you have never met to determine the soundness of your hull, and could have been the janitor for all you know....still a scary thought.


Remember, we have a 12 step program for boat restoration.
Step 1 - Deny you have a rot issue (we all do this)
Step 2 - try to convince yourself you dont have a rot issue
Step 3 - that gnawing ominous feeling that something is amiss every time you step on the boat
Step 4 - accept that you may have a XXX year old rotten boat - 37 year old in this case
Step 5 - weight your boat. Compare that weight to known dry weight
Step 6 - drill test holes (you have done this)
Step 7 - determine if the boat is worth it to you to restore, or cut up into a planter
Step 8 - pull out the implements of destruction
Step 9 - post pics of the process - we can help
Step 10 - start to loose faith, we help see the end
Step 11 - your now applying gel and buffing it
Step 12 - you are now enjoying your boat, you feel good, you realize how solid it now feels.

 

[vinnie1234]

Hi Scott. I really appreciate your thoughts. I did get some idea as to appropriate hull flex from Crestliner. I spoke with the technical department, was actually put through 3 people before I got someone with knowledge.

He agreed that the smartest way to measure flex was where I had indicated, as this is also the widest/deepest point in the hull, and located away from cross braces. Both torsional and longitudinal flex would be observable there. There are no real specifications for this, but anywhere from 0 to up to an inch would not raise any alarms in his mind, although he said most boats would be pretty close to zero. If I get an inch of flex there it's time to park it.

Although what I learned on the phone (and from this forum) made good sense to me, and assured me that I was not running a death trap, I will still take this advise with a grain of salt. Hull flex may not be my problem. The stringer condition and my front engine mount could be an issue, perhaps the drive will pull straight out at the front? Perhaps the outdrive will start to pull through the transom and bring in water? Perhaps all of the above?

I think your 12 step list is funny and clever. I am currently awaiting step 8 (I think), but there is a difference between denial and careful assessment.

Boat trips with me are pretty funny right now. I stop the boat about every 5 minutes and open up the engine compartment. I intend to continue this practice until I feel that I won't see anything new. In the meantime, I am going to think about the front engine mounts, transom and bow flex, measure and inspect on a very regular basis and be extremely attentive to every little detail that I observe when dealing with the boat.

With respect to the engine mounts, I just had the thought that perhaps I can rig up a simple safety switch in the event that they start to come loose.
I could make a switch out of washers and wires at the front mounts connect one side to engine ground, and the other side to ignition coil. Set the switch so that if the engine mounts move say - .020-.030" the switch will kill the ignition. Under power, the engine would torque upwards on the front mount, and if the ignition was cut, deceleration would have the opposite effect. In my logic this would prevent the mount from coming loose and causing more damage. If I set it with a feeler guage, then I can also tell if there is an movement after each trip.

Do you think this is a viable safety/detection system for motor mount issues? Just tossing around ideas - (again).

By the way guys - I'm not sure how I am coming off here - but I really don't want to seem like I am rejecting your advice, or the advice of any other members. I hear that you are all saying park it and do a restoration, but I can't touch a resto until february.

All this stuff that you guys have lived through and I have not. So far all of your advice has proven to be accurate. Without the information presented here by you guys - I would not have a basis with which to be cautious - I am, however a little stubborn and I like finding solutions to problems - so what you get is a thick skulled thinker who can't take no for an answer.

It's funny that with a customer vehicle I always do things by the book. The industry standard (or better If I can). With my own stuff, I like to "repair" rather than renew. I like the challenge and learn a lot about engineering/fabrication in the process. This boat is no different to me. It is a fun challenge.

THANKS!

 

[vinnie1234]

Hi Scott. I really appreciate your thoughts. I did get some idea as to appropriate hull flex from Crestliner. I spoke with the technical department, was actually put through 3 people before I got someone with knowledge.

He agreed that the smartest way to measure flex was where I had indicated, as this is also the widest/deepest point in the hull, and located away from cross braces. Both torsional and longitudinal flex would be observable there. There are no real specifications for this, but anywhere from 0 to up to an inch would not raise any alarms in his mind, although he said most boats would be pretty close to zero. If I get an inch of flex there it's time to park it.

Although what I learned on the phone (and from this forum) made good sense to me, and assured me that I was not running a death trap, I will still take this advice with a grain of salt. Hull flex may not be my big problem. The stringer condition and my front engine mount could be an issue, perhaps the drive will pull straight out at the front? Perhaps the outdrive will start to pull through the transom and bring in water? Perhaps all of the above?

I think your 12 step list is funny and clever. I am currently awaiting step 8 (I think), but there is a difference between denial and careful assessment.

At this stage in the game I can say that the advice offered here on this forum is fantastic, and you folks have proven to be correct all along the way. I have no doubt that this will prove to be the case going forward. I don't want so seem like I am not taking your advice - because I absolutely am. Without all of this information I wouldn't even know what to look for let alone how to deal with it. I agree that my boat needs a compete resto. She is rotten and I know it.

If my reality is that I have to pull the boat until winter, then so be it. But I won't be able to touch it until February. It would seem a shame to pull it now and find out then that it wasn't as bad as I thought and I could have run it all year.

My intentions are to pay very close attention to everything, with the idea in mind that I am driving a rotten boat. I will inspect, measure drill and double-check incessantly so that I am ever mindful of what is happening. My boating season will be a constant test drive. (sadly, this will also be fun for me).

I will measure my hull. If there is zero or close to zero flex I will feel good, but - I will measure it again in a couple of weeks. I will tap test the hull, because even though it doesn't tell you all is well, it will alert you to delamination and disbonds at key structural areas.

On the list of things to do, I am also going to make an engine mount safety switch. Once I figure out how to do this, I will let you know. Essentially it will cut the engine if the engine mount bolts start to move.

I am also going to install a strong bungee tether that will prevent the engine from popping up and slamming into anything if the mounts let go.

I may or may not make it to the winter without pulling the boat, but if there is an issue I am fairly confident I will see it before it happens. It is all thanks to you guys for being so awesome and helping me to understand how this all works and what to be aware of.

I look forward to yur help as I complete the 12 step process.

 

[vinnie1234]

Gotta love computers . Sorry about thatl guys, I made a post and then closed the window. THEN the post wasn't there so I made another one. Now there are two. Pick your favorite I guess......:facepalm:

 

[vinnie1234]

Gotta love computers . Sorry about thatl guys, I made a post and then closed the window. THEN the post wasn't there so I made another one. Now there are two. Pick your favorite I guess......:facepalm:

 

[GWPSR]

With respect to the engine mounts, I just had the thought that perhaps I can rig up a simple safety switch in the event that they start to come loose.
I could make a switch out of washers and wires at the front mounts connect one side to engine ground, and the other side to ignition coil. Set the switch so that if the engine mounts move say - .020-.030" the switch will kill the ignition. Under power, the engine would torque upwards on the front mount, and if the ignition was cut, deceleration would have the opposite effect. In my logic this would prevent the mount from coming loose and causing more damage. If I set it with a feeler guage, then I can also tell if there is an movement after each trip.

Do you think this is a viable safety/detection system for motor mount issues? Just tossing around ideas - (again).

It might be viable to place switches that would engage when something goes out of bounds, and have it ring an alarm or light a dash light, but you really oughtn't do anything that might result in a total loss of power at a moment when you need it most -- avoiding a hazard, making way for a non-motorized vessel, etc.

Everytime you go to the launch or marina, look around. 60% of the boats in use have the same or much worse conditions than your boat, but they just don't know it yet. The boat I bought was in use for years while it was turning to mulch underneath. Except in a paper-thin hull and rough conditions, you won't likely experience catastrophic failure unless you go looking for it.

I say be aware, but enjoy the boat responsibly this season. Equipment like PFD's, flares and a radio are not only for death traps. Even a brand-new boat can have an accident. Know what you'd do in an emergency, and keep that sense of responsibility next year after a winter of gutting and rebuilding.

You can spend rainy days this season planning, dreaming and shopping for materials, and then come Fall and early spring, you'll be a restoration machine!

 

[Scott Danforth]

Vinnie,

rigging a switch would be futile. every engine mount I know of that failed, failed at the most inopportune time, and in some cases there was not much time between that, and swimming to shore.

if you are going out. make sure your wearing a PFD and file a float plan

 

[java230]

Can you just cut the soft spot out to inspect? Then make a hatch or a quick patch on it?

 

[vinnie1234]

GWPSR, In the back of my mind, I am thinking the same thing. At the marina there is a crestliner just like mine. It appears to be in great shape, until you see how it sits in the water. The reverse chine is 2" under water and the hull cap is level with the waterline. I have looked at pictures of my model of boat in the water, and the bow is set on an upward incline from the stern, with the waterline just at, or slightly above the reverse chine at the stern. His boat is either waterlogged or loaded up with TONS of gear. My boat sits in the water just like the pictures of the new ones. (hard to believe I know) I believe mine to be in better condition than his, and he uses his boat frequently.

I think that at least around here, the vast majority of boats are basket cases and as you say, the owners are clueless.


Scott, I know you have been an active poster for a long time and no doubt know what you are talking about. With respect to the switches; why do you think that it won't work?
What am I missing?

 

[vinnie1234]

Oh Java230 - thanks for the reply. The main problem presented here is that the ONLY way to know the full extent of rot in the boat, is to pull the floor out and have a look. By look, I mean drill holes and rip stuff apart and see what comes out and what is at the bottom. For me, I am just going to skip that step entirely, gut the boat down to the hull and replace everything. Then I know I am good for another decade. I will probably end up refinishing the exterior too. why not?

The purpose of this thread, is not really to determine whether or not I need a restoration (at least not anymore). I am just an up-tight overly cautious guy that wants a new boat but can't afford one. I have zero boating experience, so I am trying to figure out a way I can do what most other boaters do and just drive the damn thing around. Knowing what I know now about these boats, I just can't leave it be. Ignorance is bliss - I guess.

 

[java230]

I agree, But it seems that cutting a 1'x1' square or something where the soft spot is might quell some of your fears if you can actually look inside and see what its like in that area.

I think A LOT of boater live in ignorance. Its the iBoats hardcores that will actually notice the soft floors etc and know what lies beneath.

 

[jigngrub]

It might be viable to place switches that would engage when something goes out of bounds, and have it ring an alarm or light a dash light,

I'd rather see it rigged to a Rube Goldberg that jabs the operator in the but with a big hypodermic needle and then when he jumps up it conks him on the head with a big wooden mallet to drive him back down on the needle again repeating the torture until the operator takes the boat out of gear.:laugh:

 

[Scott Danforth]

by the time a switch indicates that something has moved, the motor has pulled away from the mounts, most likely breaching the hull somewhere.

things go awry fast.

 

[vinnie1234]

I wasn't looking to connect an alarm, to the mount. The idea behind it is that an engine under forward power exerts upwards force on the front engine mount with the rear mount as the fulcrum. In order to accomplish this the engine must be providing a torque input to the prop. It cannot do this without an ignition system. So if I make a switch that grounds the ignition system as the engine mount lifts, then the prop will slow. This will create drag that will now exert downward force on the front engine mount. In my logic, this system should prevent the kind of catastrophic failure that happens when an engine becomes unhinged under throttle.