Is this a sea craft?

[77SceptreOB]

I agree with the multiple pump logic. I boat on a land locked medium sized lake and still have 2 pumps. A Rule 1500 and a Rule 800. Both can be operated with a manual switch. Both are also "hotwired" to the battery through an automatic float switch. JIC I also have a high water alarm. Some people call this overkill, I call it safety! BTW, my boat doesn't take on any water during dockage.

[Bigshrimpin]

http://files.dnr.state.mn.us/educati...atbuilders.pdf

coast guard regs. for boat builders . . . I believe guidlines are the same for real boat builders. A 2000lb fiberglass boat under water doesn't require 2000lbs of foam floatation to float. see pages 16 - 29.

BASIC FLOTATION. Builders of inboards and inboard-outdrives are required to
comply with the Basic Flotation portion of the Coast Guard Flotation Standard. Basic
Flotation requires a fully loaded boat to float with some portion of the boat above the
surface of the water when it is swamped. This means that the boat must contain
sufficient flotation to support two-fifteenths (2/15) of the persons capacity and 25
percent of the dead weight. Basic Flotation is designed to give the survivors of a
boating accident in which the boat has swamped something on the hull to hang onto.
The advantages of Level Flotation versus Basic Flotation are obvious (see introductory
paragraphs to Level Flotation section).
Builders of boats that are subject to the Basic Flotation requirements should perform
Steps I and II in the “Calculations section on the following pages and substitute 25
percent of their boats’ rated maximum weight capacity for Step III in the appropriate
example. Also, since Basic Flotation requires only that some portion of the boat
remain above the surface of the water, the location for the required amount of flotation
material is unimportant.

[McGillicuddy]

Nice link, Big.
Probably ought to get a sticky on this site...
Definitely getting a bookmark from me.

[KenB]

For a 17' outboard they say 20 cubic feet (or about 5 gallons of uncured foam). For a 20' inboard, they say 22 cubic feet. P. 26 suggests pouring foam down the gunnels.

How much floatation should I add? I assume what is in the stringers is enough to pass the restrictions, but how much is enough to float the boat?

Can we convert that to plain english for 20's and 23's?

[OilFieldMan]

Instead of adding foam, I'd be adding extra pumps. The way this boat sank I don't think it'd matter how much floatation foam you had it in, she was going to the ocean floor.

[Bigshrimpin]

For a 17' outboard they say 20 cubic feet (or about 5 gallons of uncured foam). For a 20' inboard, they say 22 cubic feet. P. 26 suggests pouring foam down the gunnels.

How much floatation should I add? I assume what is in the stringers is enough to pass the restrictions, but how much is enough to float the boat?

Can we convert that to plain english for 20's and 23's?

Ken - The formula breaks the equation down to 3 steps. Calculate the foam floatation required for Boat (FB) motor (FM) and People (FPC). To keep it simple we'll not use include any floatation added by coring (like transom plywood, balsa deck, etc).

Boat = 1600 x .33 (fiberglass) + weight of gear on deck (200lbs) = 728lbs/60.4 = 12 cu. ft

Motor = 352lbs (suggested submerged weight) includes battery, controls, etc. (75% of dry weight)
=352lbs/60.4 = 5.82 cu. ft

People = Still not 100% sure on this one. maybe someone can explain this.



18cu. ft of foam is enough to float a rigged 20 seacraft without people on board. If you count the transom wood and the balsa/plywood deck quite a bit less than 18 cu. ft. You can take measurements on the stringers . . . but I would guess that 4 stringers full of dry foam (pre-72 hull) would be more than enough to float that hull with the motor and people. The boat might turtle b/c of stability, but won't sink.

[red20]

I think that model was called the sink craft. All kidding aside if you own a Sea Craft and do not run 2+ bilge pumps @ 1500GPH on float switches on separate batteries you need to do so.

[TooFly]

So let's say you're 20 miles offshore and taking on enough water to keep both pumps running continuously and for whatever reason, it's taking forever to get back in and your batteries drain completely? Now what?

[OilFieldMan]

Use a manual bilge pump and if that does work put you head between you knees and kiss your ass good bye, because your going to be turtled

[strick]

if that does work put you head between you knees and kiss your ass good bye,

I cant do that any more because my stomach is too big.

strick