Finding where a Boat leaks

[rickj1]

Finding where a Boat leaks.
I have an 18 open bow boat and it leaks like a sieve.
I have filled the boat up all most the water line then put the boat up on the lift and I cannot see any water coming out of it.
The guy I bought the boat from had put a aluminum transom on the boat to make it more secure ?so he said? the boat will not leak till it is fully in the water and then fills up fast like to the top of the pump in about 30 min.
I have fully caulked the transom, but am wondering if the water might be coming in from the bottom of the motor mount ware the bolt comes through the transom. I have all so caulked that but to no avail.
Are there any tricks that someone can help me with to find the leak?

Thank you for any advice
Rick

 

[QC]

Re: Finding where a Boat leaks

Engine/motor drive combo?

 

[Texasmark]

Re: Finding where a Boat leaks

How about some details. Filling that fast should be easy to spot. If an I/O good place to look would be the boots (cracks therein) on the drive shaft and exhaust as they leave the transom and go to the outdrive.

Mark

 

[Home Cookin']

Re: Finding where a Boat leaks

need more info for possible sources.

A couple of tricks: lay paper towels or newspaper down on the bilge and see where it gets wet first.
Sprinkle baby powder around and up the sides for a similar tell tale.
Does it fill when the motor is off?
When the boat isn't running?

Leaking out doesn't always work b/c the pressure is different, and a running boat has more pressure, too, as well as more suspect places.

If it's an outboard, your transom may be flexing while running--but then again it should be out of the water, too.

 

[coastalrichard]

Re: Finding where a Boat leaks

I found my old boat leaked at the rubrail where the upper and lower hulls were joined and also at the boot on the gunwale. Also suspect would be any thru-hull fixtures or attachments. To really seal up, I've found it useful to remove fasteners and fill the hole with caulk, then install new stainless fasteners. Good luck!

 

[Don S]

Re: Finding where a Boat leaks

Are there any tricks that someone can help me with to find the leak?

There is no magic trick to finding leaks. You have to LOOK and listen for it, when it's leaking. It may take removing seats, moving things out of the way, using flashlights and mirrors and getting into awkward positions. Digital cameras can even come in handy. But it has to be done. People guessing on a forum isn't going to find it.

 

[Jeep Man]

Re: Finding where a Boat leaks

Caulking has no place on a boat

 

[smokeonthewater]

Re: Finding where a Boat leaks

Caulking has no place on a boat

Not true on so many levels

 

[5150abf]

Re: Finding where a Boat leaks

When I got my boat years ago it did the same thing and I traced it back to the livewell fill hose, it had a big split in it and being under the water line it let in quite alot of water, more when you were filling the livewells, so it doesn't have to be the hull leaking.

 

[oops!]

Re: Finding where a Boat leaks

is this a glass boat?....or metal?

 

[rickj1]

Re: Finding where a Boat leaks

It is an outboard and I like the ideal of maybe just placing some paper on the out side of the boat and seeing if it is getting sucked in at any one place. I all so like the ideal of taking out all the threw hull bolts and filling with caulk and replacing them.
The boat takes on water just when it is put in the water. That is why I am so baffled on ware it is coming in.
I will all so try the plug on the out side of the live well and see if that might help.
As much water and as fast as it comes in you would think it was easy to find but not.
Any way thank you all, for the ideals.

Rick

 

[southkogs]

Re: Finding where a Boat leaks

For clarification: The boat has always leaked since you've owned it, correct?

How many "on purpose" holes do you have on the boat? Drain hole above the keel on the stern (with correct plug in), a live well vent and what else? Bilge vent?

 

[Andy'sDelight]

Re: Finding where a Boat leaks

If it is taking on water while sitting, then check every underwater fitting and hose running from those fittings. Are your underwater through hull fittings stainless or bronze, or are they the cheap plastic vinyl ones? If so look for tiny cracks (or obviously big ones) in the through hull. If there is even the most minute crack it will take on water and can sink your boat fast. Lastly are you putting the plug in before putting it in the water? I know it may sound elementary, but I have seen posts in the past where that was asked only to have the OP respond "what plug".

If you are certain that none of your thru hulls are leaking and you have put the plug in, then check the fitting where the plug goes in. If it is not a screw in plug but rather one of those plugs with the lever that you flip up to expand the rubber part, I have seen many times where the plastic through hull fitting where the plug goes in cracks and then actually falls out of the hole. This not only can be a source of a leak, but it will begin to rot your transom as well since the wood core is likely exposed. If this is the case, fix it ASAP.

Again, you are saying it takes on water as soon as she goes in, just floating there. That makes it a little easier to find the leak since you KNOW it is not from splashing under the rub rail or splashing over the transom from the engine while underway.

I also just noticed that you stated the PO put an aluminum "transom" on. Is that the ENTIRE transom or just a transom saver aluminum piece on the inner side where the bolts go through? Transom savers are fairly common on older boats, especially if it has been repowered. Old outboards that have been hanging on the boat for years put alot of torque on those washers, and they tend to dig into the fiberglass after many years. When repowering it's pretty common that mechanics will load up the holes with epoxy or 5200 and put the aluminum transom saver plate on to alleviate stressing the fiberglass further with just washers. This should NOT be a source of leakage. If it is, you have far greater problems than just water in the bilge, you have an entire transom repair on your hands.

 

[Andy'sDelight]

Re: Finding where a Boat leaks

Here's a couple great examples of a plastic thru hull that will sink you. They look pretty harmless, don't they?

 

[Home Cookin']

Re: Finding where a Boat leaks

um, the paper goes on the inside.

Start with a sponge-dry bilge.

Depending on how you launch you may be getting water in as the boat enters the water, but i think you said you have a steady increase. Shipping water on the launch is a frequent problem with tilt and some roller trailers.

 

[island mike]

Re: Finding where a Boat leaks

A friend of mine had the same problem with his boat,After searching for a long time we found out that it was indeed the drain plug(the bronze screw in type) check yours out..It may be the same problem.Hope this helps..
I mike

 

[oops!]

Re: Finding where a Boat leaks

rick.......

i fix boats with holes in them for a living.

is this a fiberglass boat or an aluminum boat?

leaks are different in the two boats......we cannot advise you correctly unless we have more basic information.

leak down tests are similar, and what the guys are saying is true......but if this an aluminium boat with rivets......its a whole different story.

we need to know, or we are just shooting in the dark
we also need to know if the boat has a livewell on it or if it has thru hull fittings. if you dont know what a live well is....then chances are you dont have one. but if you have any fittings like posted in post 14....(there will be one from the bilge pump)....but what about under the water line?

cheers
oops

 

[ezmobee]

Re: Finding where a Boat leaks

The guy I bought the boat from had put a aluminum transom on the boat to make it more secure “so he said” the boat will not leak till it is fully in the water and then fills up fast like to the top of the pump in about 30 min.

This was done as a band-aid over a failed rotten transom. All the fasteners going through the rotted wood are likely leaking. A new transom, which you most likely need anyway, will probably solve your issue.

 

[Andy'sDelight]

Re: Finding where a Boat leaks

This was done as a band-aid over a failed rotten transom. All the fasteners going through the rotted wood are likely leaking. A new transom, which you most likely need anyway, will probably solve your issue.

That's a mighty jump to conclusions. I know many mechanics that will automatically add an aluminum transom saver for any repower they do to ensure that the washers don't eat into the fiberglass.

 

[rickj1]

Re: Finding where a Boat leaks

It is a fiberglass and I have two live wells but I never see any water in them I have all so changed all the plugs but I will take a look at the plug holes (ware the plug goes into) it has thru hull fittings under the boat.
Thank you for all the help.The boat is on a lift so that is how it goes into the water
Rick