Boat weight

[Bill3434]

I hope someone can help with this problem. I have a 1970 16ft Sportcraft C-Gull and I suspect I have wet foam. I have so far figured my weight on truck scales at 1098lbs. Their are two items that I don't have weights on is the metal plate on the rear to re-enforce my transom and two pieces of plywood. One piece it part of my deck, I do not yet know if it is over the original deck or is the deck (winter project). The other smaller piece is about 4ft X 5ft placed on top of the deck piece to support my fishing seat. I did not take out the regular seats (lounge type) out of the boat. Everything else was removed.

I have several questions I hope someone can help me with.

1. What was the density of the foam used in the early 70's? I know they have pourable foam as light as 2lbs/ft cubed.

2. Based on what little I can find I have have 100-150lbs I can't account for. Am I in the ballpark.

3. I have a '77 Johnson 70hp the prop is properly matched 15in @5500rpms average 28mph sometimes hit 30mph (gps). I had a similar style boat as a teenager except it was 18ft with a 50hp and would hit 35mph(no gps back then).

I just would like to know before I start tearing into it this winter. Kind of got hooked on this boat with all the elbow grease I have put into it and the headaches she has given me.

 

[smokeonthewater]

Re: Boat weight

Well the plate on the transom and the floor patches are red flags but 100-150 lbs is pretty much nothing.... Majorly waterlogged foam I'd suspect would hold at least several hundred lbs

 

[Bill3434]

Re: Boat weight

Well the plate on the transom and the floor patches are red flags but 100-150 lbs is pretty much nothing.... Majorly waterlogged foam I'd suspect would hold at least several hundred lbs

That's the reason for the winter project. I'm just trying to learn all I can before I start tearing into to it. I did read in a forum on this site or somewhere else where a guy with a similar type boat pulled almost 600lbs of wet foam out. That got me motivated to weigh the boat to see what I had.

As a side note my boat man put the plate on for me as a temporary fix. I know it's got to be repaired.

 

[NYBo]

Re: Boat weight

If your calculations are correct, that's 12 to 18 gallons of water weight (approximately 8.3# per gallon). Not a horribly heavy load, but your safety factor is reduced a little: that weight is in the worst place as far as maintaining level flotation in case of swamping is concerned. But my biggest concern would be any wood that is in contact with the wet foam. Rot, like its kinfolk rust, never sleeps!

 

[zopperman]

Re: Boat weight

My saturated foam came in at about 320 pounds.

You likely have wet foam if you have a rotted floor...

my 70 HP pushes my 18' bowrider 30 MPH at WOT. You could also have motor issues, but you really need to fix the structure of your hull.

We can help in the dry dock...

 

[Bill3434]

Re: Boat weight

If your calculations are correct, that's 12 to 18 gallons of water weight (approximately 8.3# per gallon). Not a horribly heavy load, but your safety factor is reduced a little: that weight is in the worst place as far as maintaining level flotation in case of swamping is concerned. But my biggest concern would be any wood that is in contact with the wet foam. Rot, like its kinfolk rust, never sleeps!

That's why I'm going to be tearing out the deck. The boat has lasted 41yrs so far like for it to last as long as me. You wouldn't happen to know anything about the density of the foam used in the early 70's.

 

[Bill3434]

Re: Boat weight

My saturated foam came in at about 320 pounds.

You likely have wet foam if you have a rotted floor...

my 70 HP pushes my 18' bowrider 30 MPH at WOT. You could also have motor issues, but you really need to fix the structure of your hull.

We can help in the dry dock...

Engine is fine once started she's a little cranky when cold but after that she runs great. She has no problrem getting the boat on plane and running 5500rpm.

That's my winter project is to repair or replace the deck, new foam and structural repair if needed already know transom has to be worked on.

Thanks for the info on your boat though that gets me in the ball park when it comes to my speed.

I'm almost hoping I got lots of wet foam in the boat so I can make it lighter. Just don't need the other issues that come with wet foam though.

 

[oops!]

Re: Boat weight

That's why I'm going to be tearing out the deck. The boat has lasted 41yrs so far like for it to last as long as me. You wouldn't happen to know anything about the density of the foam used in the early 70's.

2 lb pour in foam mist likely.

in the early days of boat building they used big chunks of Styrofoam or what ever they could get there hands on.
but by the early seventies, they had pretty much switched to pour in.

but what type of foam, how much is of little consequence at this point.
the weight in your boat may not all come form waterlogged foam, rotten decks and stringers are very very heavy.

start a thread in the restorations section and we can guide you to a proper, successful rebuild.
for a 19 footer, the approximate costs are around 2k. but this money can be spent bit by bit, so it does not hurt all at once.

one thing, i would suggest that you start investigating on different types of plywood, get some, and get it drying. A.S.A.P.
the dryer the better

 

[Bill3434]

Re: Boat weight

2 lb pour in foam mist likely.

in the early days of boat building they used big chunks of Styrofoam or what ever they could get there hands on.
but by the early seventies, they had pretty much switched to pour in.

but what type of foam, how much is of little consequence at this point.
the weight in your boat may not all come form waterlogged foam, rotten decks and stringers are very very heavy.

start a thread in the restorations section and we can guide you to a proper, successful rebuild.
for a 19 footer, the approximate costs are around 2k. but this money can be spent bit by bit, so it does not hurt all at once.

one thing, i would suggest that you start investigating on different types of plywood, get some, and get it drying. A.S.A.P.
the dryer the better

Thanks for the info on the foam I couldn't get any good information about that. Didn't need to hear that about the stringers though. I'm trying to cut every pound out of the boat so I can add more stuff like trolling motor and another battery.

I will be posting in restore area of the forum once I start the work. Just trying to learn all I can before I start so I won't have lots of surprises and if I do I have a clue as to where to go when I come upon them. Not sure I would call my work a restor though, I just want a functional boat so I can fish and relax.

 

[oops!]

Re: Boat weight

click the link in the bottom of my sig and start reading.......any question that was ever asked on a boat is fully covered by experts in there.

the first 16 pages pertain to it areas you need

 

[Bill3434]

Re: Boat weight

click the link in the bottom of my sig and start reading.......any question that was ever asked on a boat is fully covered by experts in there.

the first 16 pages pertain to it areas you need

Thanks for the info. More reading to do, more interesting than my college work.

 

[Bill3434]

Re: Boat weight

click the link in the bottom of my sig and start reading.......any question that was ever asked on a boat is fully covered by experts in there.

the first 16 pages pertain to it areas you need

You should have told me after reading the first 16 pages i would read all 173 pages. Great job on the extension. Lots of info.