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hi everyone jeff cote here with another

session of boatingtechtalk.com

we've got a question from a fellow voter

named gerald gerald says jeff i've been

watching all of your videos thank you

there's quite a lot

thank you all right thank you as well my

questions are

how do i know if my boat has a bad

ground

oh

that's like the meaning of life right

there that's not an easy question um i

got that question in my inbox and i was

like i gotta answer that question it's a

hard one so

if i'm not gonna answer all of it in

this five or four minutes just know that

it's because it's not easy so first of

all let's define grounds

right what does gerald mean by grounds

well there's a lot of different grounds

on a boat there could be a dc negative

should be grounded ac should be grounded

your bonding system should be grounded

some boats have rf grounds right

um

and so

there's different types of grounds and

what makes them grounds is that they're

all connected to a common point right so

that's why a lot of times we call that

common

right common grounds

so they all should be at the same

potential and they do that by actually

being interconnected to one another

actually literally interconnected on

most of our boats we actually use the dc

negative

as the ground and everything connects

back to that at one single point

including the bonding system maybe even

the rf ground and the ac ground

so in most of our boats although

conceptually it would be a great idea to

have literally a bus bar called grounds

and having one connection to dc negative

another connection to ac ground another

connection to your rf ground another

connection to your maybe your bonding

ground right having all that in one

place would be great but unfortunately

most of us don't have that it's just not

like that they're going to use on our

boats the dc negative and they're going

to make that ground and they're going to

do that by having a connection to ground

and again that connection to ground is

generally through the engine block but

not necessarily right some boats have

a flexible shaft coupler at the back of

their transmission and they don't have a

ground

all right so now that we've defined the

different types of grounds

most likely this situation is and we can

assume when we say grounded

the implication is most likely how do i

know if my dc negative system is

connected to the water that's ultimately

what you're looking to right you're

looking for a path you're looking for a

path between the dc negative and the

water to make sure that your dc negative

is not just a dc negative but it's a dc

ground right

otherwise you have this floating voltage

right so yeah there is a delta on your

battery post every battery is not every

single battery is when we buy it as an

individual unit has two posts on it

right a negative and a positive we're

talking about a delta between the two

but the negative is not ground unless

it's connected to ground

in homes in north america and apartment

buildings commercial buildings you know

you're gonna i've heard of the stake

being at the ground and there's they're

grounding the ac ground

near the building

well on boats what we do to ground is we

generally go through the engine block

through the transmission

through the propeller shaft

and that is our connection to ground

so one way you could measure if your

boat is grounded um is uh and this you

have to know what you're doing but you

would actually

measure uh resistance right across your

dc ground and your ac ground and they

should be built at the same potential

right there should be path basically

they should be equal there should be no

delta because they're both connected at

the same point

right so that is one way of checking

you could also have a reference anode

there's various things but ultimately

the most important thing to check here

would be connecting i would use probably

a shore power connection or look for the

connection itself make sure that if your

boat is out of the water you could

literally put a multimeter lead right

and see maybe take a multimeter and do

an ohms test between the propeller shaft

and your engine block and doing the

engine block to your engine battery and

your engine battery should be connected

to your engine block because otherwise

your starting circuit wouldn't work so

really what you're wondering is

continuity from the engine block

to the propeller shaft right and put a

resistive

ohm setting on your multimeter and

measure to see and make sure that you've

got good connectivity you'll actually

see some boats they have even a little

strap

right across a flexible shaft coupler so

that they don't actually lose

the conductivity

and their path to ground

that's probably how i would do it any

one of you have other suggestions on how

you would go about actually measuring

ground on your boat and wondering if

your boat is grounded please share your

experience down below and thanks for all

of you for watching i want to thank you

for watching this video don't forget to

subscribe if you want to get more of

this cool content and also check out our

website if you've got questions that are

unanswered we've actually taken the time

to answer quite a few questions and you

might be surprised to find the answer

right there on our website so thanks

again

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