Boat taking on water

I have a Wellcraft 18 foot boat with a Mercruiser 470 I/O engine. I took it out last weekend and the boat ran fine all day. However, when we left our last fishing spot, I couldn't get the boat to plane regardless of tilt and trim adjustment. After trying three or four times, I noticed water coming from the engine housing and realized the boat had taken on a lot of water. The storage compartment in the floor was full also. Yes, the plug was in and there are no holes in the hull anywhere. The hull is in great shape. When we got to the boat ramp (towed in because the boat wouldn't stay running due to the water depth in the engine compartment I'm guessing) and I took the plug out, there must have been 500-600 gallons of water in the hull. Does anyone have any idea what could cause this? The only thing I can think of is that water is getting in between the outdrive and the transom but I've never had this problem before and can't see any obvious area that the water would be getting in. By the way, after all the water was drained, the engine started and ran fine. Any ideas would be greatly appreciated!!!

Thanks,

Mike P.

Re: Boat taking on water

We could venture guesses as to what is leaking all day (and month) long, and someone would be right. But the fact is, you MUST put the boat back in the water and LOOK, and LISTEN, for a leak. Leave it on the trailer and start searching.
BTW. With a boat, it a common practice to have a bilge pump with a float switch to come on automatically if the water level comes up too far.
Do you have one? Do you ever check it to see if it works?

Re: Boat taking on water

18 footer must have a bilge pump.... laws in Arizona anyway.

Re: Boat taking on water

Wow! Let me just re-iterate what Don said before I venture a guess. I watched a boat sink on July 4th weekend under almost the exact same conditions. Only problem was, I was towing it, and I was lucky to have had a HUGE knife, to cut loose. Always carry a big knife that can cut a rope quickly. Pound on the rear of the transom with the boat out of the water and look for a rotted transom...it will sound hollow, as opposed to the solidness of 2 inch MDF, like a good transom. Water can get in that way, around the drive. It might be a vent also, if installed below the water line? Check the thru hull exhaust if applicable?....If it looks like a fish-----

Re: Boat taking on water

The boat has a bilge pump but apparently doesn't come on automatically. It may be a law here in Texas too, but it must not have been in 1987! I turned the bilge on when I realized there was water but at that point there was a lot of water. Keep in mind that no water was visible until I started trying to move. It was all in the hull out of sight. It came out of the engine compartment when we took off.Transom is in great shape. I was told it may be the upper bellow letting water in and was just wondering if anyone else might have ventured the same guess. I guess I'll put her back in the water to investigate more. I've been boating all my life but have always had outboards. I was forewarned that I/O's are much more high maintenance than outboards but bought it anyway...big mistake!!! My last outboard was in the shop once in ten years. I always flush the lower unit when I get the boat out of teh water and never even had to replace the impeller on the outboard. Bought this boat (I/O) used five years ago from the original owner, always garage kept and very clean with all maintenance records. It's been in the shop probably 8 times in the five years for one thing or another. Have probably spent almost as much maintaining it as I paid for the boat.

Re: Boat taking on water

You either Need a Bilge Pump that Works,...... Or a Bigger 1............
Unless there was water FLOODING into the boat,......
A Normal sized Bilge Pump should have been able to Pump Out the boat,+ you Should have been able to power up,+ Go Home.......

And,........
By the sounds of your post,........
You've had this boat 5 Years,+ have done NO Preventive Maintenance...........

Re: Boat taking on water

if it was my boat, 1st thing i'd do would be to check the bellows. the top one that the drive shaft goes thru, and the shift cable bellows. the small one. ya should be able to see fairly well with the drive up. look close. might check all other hoses inside the engine compartment. make sure they aint leakin too and just fillin ya up whilest yer running... seems like ya could do these checks on land. if ya still can't find anything, through it in the drink and start lookin and listenin like dons says....with that much water, surely ya will find the leak then.
oh, my 19'er has a bilge pump but aint auomatic....i would like one of themz for peace of mind.....
yep, from what i read. i/o's are high maint. and like bondo says. ya need to do some pm on them regularly....it seems to be the nature of the beast.....
ya might want to try to dry out the inside of yer hull too. don't know how, but do know that water under the floor will start attackin yer exposed wood under there and will lead to much disappointment (rotted stringers). maybe get the bow real high on land, inject air into the void between the floor and the hull. dought ya will ever get it dryed out. but at least ya made the attempt...

Re: Boat taking on water

Actually I have done routine preventive maintenance. Maybe my post was a little confusing. It was my outboard that never needed maintenance. Ran perfect year after year.With the I/O, I've tuned up twice in five years, replaced the water pump once, impeller two years later and then all of the other things that have come up unexpectedly (upper and lower seals , starter, etc.). By the way CPO, have you ever changed bellows yourself? Is it something a guy with average mechanical skills could do? Thanks for the feedback everyone!

Re: Boat taking on water

Bellows can be done by a DIY mech. I did my own. The factory service manual and patients are a must. I did mine over a weekend took between 7 and 8 hours (no beer breaks). Next time I figure I can cut 2 to 3 hours off. There was a great post here by tommays a while back on the whole procedure. But I cat find sheet with this upgraded boards search function. Maybe some one saved a link to it and will post it here for you. Good luck.

Re: Boat taking on water

hum, i guess i'm cpo. really puttin me on the spot mike p.
, no i have not, so have no practical experience at bellow R&R. i've read the procedure many times(oem service maunal) and have not got up the nerve to R&R them. the method for R&R seems complex to me in reading it. mostly the hinge pin part and the nail part. i've got the nla small nails too. the bellows are the only thing between me and sinking. so. so far. i've had them inspected by the merc. dealer and may have them do it when it becomes time for me to be ontoit . i really do want that part done right when it comes time to do it. also i think it may require some special tools if i remember the read right. at the very least a drive shaft alignment tool. which i don't have. bondo and dons, and many others, other than me, are yer guys if ya want info on R&Ring them. i'm guessin they've done so many bellows replacements they probably can't remember one from the other.
i consider myself slightly abouve average when it comes to mech. skills and that's where i stand on that....at this point and time anyways...
really brought out my lack of experience on that question mike.... oh well, that's why i'm on this board too. to learn from others. and if i can, help others with what knowledge and experice that i do have. you can inspect the outside of yer bellows w/o any tools at all and from yer discription, if yer bellows are spent, letting that much water in. ya may be able to see that from the outside, may not be able to too, but it's seems like a quik easy start as to locatein yer problem.....

Re: Boat taking on water

It is indeed the drive shaft bellow. I decided that since the outdrive has to be removed for replacement, I'll go ahead and replace the shift cable and shift cable bellow also. From what I hear, a bad shift cable bellow will let water in even much faster than the drive shaft bellow. I'll be back on the water tomorrow. Thanks for everyones help. This is a great website...glad I stumbled onto it. Great source of info.

Mike P.

Re: Boat taking on water

This is indeed a great site. It has helped me many times. For what it is worth, here is another that has some good info as well - especially on "how to" do various things: http://mercstuff.com/howdoi.htm

Re: Boat taking on water

Mike said:

It is indeed the drive shaft bellow. I decided that since the outdrive has to be removed for replacement, I'll go ahead and replace the shift cable and shift cable bellow also. From what I hear, a bad shift cable bellow will let water in even much faster than the drive shaft bellow. I'll be back on the water tomorrow. Thanks for everyones help. This is a great website...glad I stumbled onto it. Great source of info.

Mike P.

Click to expand...

You should Also replace the Shift Cable itself,........ You're about Due.......

And,..........

You Still need a Bigger Bilge Pump,..................... That Works..................d

Re: Boat taking on water

ive got two 1250's and a smaller one that will get out what the big ones dont out of the bilge. theres an equation posted here somewhere on how big of hole so far under water will let how much water in your boat. its surprisingly a very large amount only inches under water. and if that outflows your pump..........so just beacuse the bilge has a pump...doesnt mean its big enough to work properly. sounds like you found that out. in my big boat i have an electric sump pump just in case running off my inverter.