Boat Plans Uk
During this week, you may have noticed that we’ve changed the overall appearance of our website. Over the past year, our website was getting so large, that it was becoming cumbersome to manage and probably the same for you to view. So after a lot of thought, we decided to condense the overall “workings” of the site to make it more user friendly and easier to use. I hope you like it.
BILGE PUMPS
Talking with Graham recently (Graham is building the SportzMaster 19), the subject of bilge pump systems came up. As we all know, bilge pumps would have to be on the top of the list for any boat. Failure to do so can result in water damage, loss of stability, and even sinking. Even so, water will find its way aboard through drips in windows, through hatches and ventilators, and through spray or rain entering an opening. In rough weather, solid water will come on deck, finding its way below through everything from chain pipes, hatch gutters or to a door left open for to long.. Then of course there are leaks in the hull itself. These could be small drips through packing glands, damaged fittings, or- the worst fear- a sizable hole from a major impact. As we’ll see even a seemingly quite small hole below the waterline can admit a substantial amount of water very quickly.
REQUIRED BILGE PUMP CAPACITY:
There aren’t many regulations for pleasure craft pump capacity. We can refer to the ISO 15083-2003 (categories A,B and C recreational boats) and AS1799 standard for some guidance.
GPM – gallons per minute
LPM = litres per minute
ISO boats less than 19.6ft (6m): = 2.6 GPM ( 10 LPM or 600 litre per hour)
AS1799 boats less than 33 ft (10m): = 17.44 GPH (66 LPM or 3960 litres per hour)
As you can see, there is quite a variation in minimum bilge pump capacity requirements.
ESTIMATING FLOODING RATE FROM HULL DAMAGE:
The minimum recommendations for bilge pump capacity seems to low. We can check the minimum required pump capacity against the approximate flooding rate from a rather small hole in the hull below the waterline. The following is a reasonable approx formula for flooding rate:
GPM = 5.56 x d^2 x (sq.rt)H
Or
LPM = 2.08 x d^2 x (sq.rt)H
d = approx opening diameter, in or cm
H = depth of opeing below the waterline (head), in or cm
Example:
Let’s assume a simple puncture of approx 2” (50mm) diameter located 6 in (152 mm) below the waterline for a power boat or yacht.
5.56 x 2^2 x (sq.rt)6 = 54.47 GPM
Or
2.08 x 5^2 x (sq.rt)15.2 = 203 LPM
If you were unlucky enough to get an impact 1.5 ft down ( 457mm) with the same hole diameter, then the amount of water pouring in would be approx 94 gallons per minute or 351 litres per minute !
“Whoops - unless you have some form of foam flotation or sealed air compartments, …your going down, unless your boat is made from wood”. Even still, you would still want to have the capacity to pump the boat out faster than the water is coming in !
You can quickly see however, that even a hole of modest size (and not all that deep) will quickly exceed the minimum bilge pump capacity required above. There are practical limits to how large a bilge system you can and should install, but I recommend more than the minimum requirements above.
SIZING UP A BILGE PUMP FOR THE REAL WORLD
Many manufacturer’s bilge pump capacity ratings aren’t all they ought to be. Most manufacturer’s rate their pump capacity with no hoses attached and with no lift (head). Those that do rate for head state this clearly, and it’s usually a nominal 10-ft of 3-metre head or height. However, not a boat in existence operates a bilge pump with no lift or hoses attached.! Also, the friction in 3 to 6 feet (1 -2 metres) or more of hose and pipe commonly found in all bilge systems cuts the flow rate, and the batteries are seldom delivering full oomph.
Manufacturer’s rate capacity in gph (gallons per hour) or gpm (gallons per minute); or in metric lph (litres per hour) or lpm (litres per minute) Unfortunatly, that shiny new pump rated at, say, 1,500 gph (5,700 lph) in the catalog will seldom deliver more than half that in a real- sevice installation. Indeed, 40 percent of rated capacity is about the norm. In other words, the real flow out the thru-hull outlet from this 1,500-gph (5,700 lph) pump will be about 600 gph (2,280 lph)
Allowing for this loss in flow rate, what’s the minimum pump capacity that should be installed? The following will give sensible results.
Pump Capacity (gph) = 1000 + (100 x displacement in long tons)
Or
Pump Capacity (lph) = 3,785 + (372 x displacement in metric tons)
Example:
Assuming a boat has a displacement of 2200 lbs (998 kg or .998 metric tons)
Long Ton = 2240 lbs
2200 lbs / 2240 = .982 long tons
1000 + (100 x .982) = 1098 gph or 1098 gph / 60 minutes = 18.3 gpm
Or
3,785 + (372 x .998 metric tons) = 4156 lph or 4156 / 60 minutes = 69.27 lpm
This is the minimum power-driven pump capacity (manufacturer’s rated capacity; we’ve allowed for 40 percent efficiency) that should be fitted. If you have less capacity, get a bigger pump or an additional one.
To avoid large amperage draw on the batteries, install the larger high capacity pumps on pads to lift them about 5 inches (125mm) above the lowest point in each bilge compartment, with each pump’s automatic float switch up on the same level. Small –capacity submersible pumps are located right at the lowest point in the bilge sump in each compartment, with their auto foat switches at their level. In this way the smaller, low powered pumps handle the vast majority of routine bilge pumping. This reduces battery draw. In the event of a serious flooding situation, the water rises high enough to trip the upper-capacity bilge pumps.
Hope this helps out.
Have a good one
Mark
LATEST LAUNCHING
Toms Mushulu 12
Having been very busy with other commitments I finally finished building the Mushulu 12 and set of to the Hawkesbury river boat ramp to launch my boat. It was my birthday and we had booked a house on the Island Bar point, so that we could launch and use the boat as an exiting transporter and fishing vessel for the weekend.
Unfortunately the weather was very windy and rainy, but we had to launch her and get on with the day.
A couple of old sea dogs were cleaning their catch beside the boat ramp, and commented that my boat was too small for the Hawsburry and that the boat seemed out of proportion to its length. I polity answered back stating that I had built it myself and that it was a certified vessel. They briefly smirked and watched as I launched her into the bay.
When we had all the food, wine, fishing rods and my beautiful girlfriend on board I started my 15 hp merc and let it rip, she went onto a plane straight away, and it felt so comfortable and great to handle.
I turned around gave a few circles around the old sea dogs and past their old dirty tinny, and asked them what they thought, they were all surprised and had nothing to say, I understood why, I had build a beautiful boat, had a beautiful girl with me and three days to enjoy my boat, I was in heaven !
Thanks Mark !
Tom Macens.
You can see more of Toms Launch Day plus his video of his Mushulu 12 out on the water
on our Latest launchings page
To see more of his build photos, please vist our Boatbuilding Forum
OUR RIPTIDE 457:
We managed to get back into the shed again and finished glassing the boat. Then it was time to sand and then bog and begin fairing up the boat ready for painting the bottom panel. Well then turn the boat over and paint the transom and topsides later after the interior is finished.
Here weve bogged the boat up ready for the first stage of fairing.
You can see more of our build in our
Workshop News
For more information about the Riptide 457,
please visit our Website
GRAHAMS SPORTZMASTER 19:
Graham sent in his latest build pictures late today. Graham works on his boat for around 3 hours a day he told me, just taking his time. At the rate that hes building, I give him...6 weeks and well probably be launching !
Graham is now installing his fuel tanks, laying out bilge pump systems and other electronics (Depth sounder etc)
To see more of his latest build photos, please vist our Boatbuilding Forum
For more information about the SportMaster 19,
please visit our Website
PHILS RIPTIDE 457
Phil has been a bit quite of late helping out his brother who got hit with the Brisbane floods, but its good to see hes back into building his RipTide 457 again.
Hi Mark,
Sorry Mark i have been to busy trying to make a quid !!!! LOL
Bow hook 470mm worked like u said
thanks
regards
Phil
He rang the other day enquiring about instead of having the boat remote steered, would it be possible to make it tiller steered. Talking on the telephone, Phil explained what he wanted and listening to his requirements as he plans on operating the boat in open waters and the Brisbane Bar for fishing, were presenting helping him to change certain aspects of the design to suit his needs.
To see more of his latest build photos, please vist our Boatbuilding Forum
For more information about the RipTide 457 design,
please visit our Website
--------------------------------------------------------------------
See you next week with more of our Latest News and other articles !
Thanks for visiting our website?????????????
http://www.bowdidgemarinedesigns.com/
BILGE PUMPS
REQUIRED BILGE PUMP CAPACITY:
There aren’t many regulations for pleasure craft pump capacity. We can refer to the ISO 15083-2003 (categories A,B and C recreational boats) and AS1799 standard for some guidance.
GPM – gallons per minute
LPM = litres per minute
ISO boats less than 19.6ft (6m): = 2.6 GPM ( 10 LPM or 600 litre per hour)
AS1799 boats less than 33 ft (10m): = 17.44 GPH (66 LPM or 3960 litres per hour)
As you can see, there is quite a variation in minimum bilge pump capacity requirements.
ESTIMATING FLOODING RATE FROM HULL DAMAGE:
The minimum recommendations for bilge pump capacity seems to low. We can check the minimum required pump capacity against the approximate flooding rate from a rather small hole in the hull below the waterline. The following is a reasonable approx formula for flooding rate:
GPM = 5.56 x d^2 x (sq.rt)H
Or
LPM = 2.08 x d^2 x (sq.rt)H
d = approx opening diameter, in or cm
H = depth of opeing below the waterline (head), in or cm
Example:
Let’s assume a simple puncture of approx 2” (50mm) diameter located 6 in (152 mm) below the waterline for a power boat or yacht.
5.56 x 2^2 x (sq.rt)6 = 54.47 GPM
Or
2.08 x 5^2 x (sq.rt)15.2 = 203 LPM
If you were unlucky enough to get an impact 1.5 ft down ( 457mm) with the same hole diameter, then the amount of water pouring in would be approx 94 gallons per minute or 351 litres per minute !
“Whoops - unless you have some form of foam flotation or sealed air compartments, …your going down, unless your boat is made from wood”. Even still, you would still want to have the capacity to pump the boat out faster than the water is coming in !
You can quickly see however, that even a hole of modest size (and not all that deep) will quickly exceed the minimum bilge pump capacity required above. There are practical limits to how large a bilge system you can and should install, but I recommend more than the minimum requirements above.
SIZING UP A BILGE PUMP FOR THE REAL WORLD
Manufacturer’s rate capacity in gph (gallons per hour) or gpm (gallons per minute); or in metric lph (litres per hour) or lpm (litres per minute) Unfortunatly, that shiny new pump rated at, say, 1,500 gph (5,700 lph) in the catalog will seldom deliver more than half that in a real- sevice installation. Indeed, 40 percent of rated capacity is about the norm. In other words, the real flow out the thru-hull outlet from this 1,500-gph (5,700 lph) pump will be about 600 gph (2,280 lph)
Allowing for this loss in flow rate, what’s the minimum pump capacity that should be installed? The following will give sensible results.
Pump Capacity (gph) = 1000 + (100 x displacement in long tons)
Or
Pump Capacity (lph) = 3,785 + (372 x displacement in metric tons)
Example:
Assuming a boat has a displacement of 2200 lbs (998 kg or .998 metric tons)
Long Ton = 2240 lbs
2200 lbs / 2240 = .982 long tons
1000 + (100 x .982) = 1098 gph or 1098 gph / 60 minutes = 18.3 gpm
Or
3,785 + (372 x .998 metric tons) = 4156 lph or 4156 / 60 minutes = 69.27 lpm
This is the minimum power-driven pump capacity (manufacturer’s rated capacity; we’ve allowed for 40 percent efficiency) that should be fitted. If you have less capacity, get a bigger pump or an additional one.
To avoid large amperage draw on the batteries, install the larger high capacity pumps on pads to lift them about 5 inches (125mm) above the lowest point in each bilge compartment, with each pump’s automatic float switch up on the same level. Small –capacity submersible pumps are located right at the lowest point in the bilge sump in each compartment, with their auto foat switches at their level. In this way the smaller, low powered pumps handle the vast majority of routine bilge pumping. This reduces battery draw. In the event of a serious flooding situation, the water rises high enough to trip the upper-capacity bilge pumps.
Hope this helps out.
Have a good one
Mark
LATEST LAUNCHING
Having been very busy with other commitments I finally finished building the Mushulu 12 and set of to the Hawkesbury river boat ramp to launch my boat. It was my birthday and we had booked a house on the Island Bar point, so that we could launch and use the boat as an exiting transporter and fishing vessel for the weekend.
Unfortunately the weather was very windy and rainy, but we had to launch her and get on with the day.
A couple of old sea dogs were cleaning their catch beside the boat ramp, and commented that my boat was too small for the Hawsburry and that the boat seemed out of proportion to its length. I polity answered back stating that I had built it myself and that it was a certified vessel. They briefly smirked and watched as I launched her into the bay.
I turned around gave a few circles around the old sea dogs and past their old dirty tinny, and asked them what they thought, they were all surprised and had nothing to say, I understood why, I had build a beautiful boat, had a beautiful girl with me and three days to enjoy my boat, I was in heaven !
Thanks Mark !
Tom Macens.
You can see more of Toms Launch Day plus his video of his Mushulu 12 out on the water
on our Latest launchings page
To see more of his build photos, please vist our Boatbuilding Forum
OUR RIPTIDE 457:
Here weve bogged the boat up ready for the first stage of fairing.
You can see more of our build in our
Workshop News
For more information about the Riptide 457,
please visit our Website
GRAHAMS SPORTZMASTER 19:
Graham is now installing his fuel tanks, laying out bilge pump systems and other electronics (Depth sounder etc)
To see more of his latest build photos, please vist our Boatbuilding Forum
For more information about the SportMaster 19,
please visit our Website
PHILS RIPTIDE 457
Hi Mark,
Sorry Mark i have been to busy trying to make a quid !!!! LOL
Bow hook 470mm worked like u said
thanks
regards
Phil
To see more of his latest build photos, please vist our Boatbuilding Forum
For more information about the RipTide 457 design,
please visit our Website
--------------------------------------------------------------------
See you next week with more of our Latest News and other articles !
Thanks for visiting our website?????????????
http://www.bowdidgemarinedesigns.com/
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