| Numerical methods for calculating minimum flotation requirements for inboard powered vessels | |||||||||||||
| (a) | Conversion Factors | ||||||||||||
| lbs to kg | 0.4536 | ||||||||||||
| kg to lbs | 2.205 | ||||||||||||
| m3 to 3ft | 35.31 | ||||||||||||
| Foam density of 1 m3 of foam | 32.14 | kg | |||||||||||
| (b) | Specifications | http://www.glen-l.com/designs/inboard/hotrod.html | |||||||||||
| Item | Lbs | Kg | Refrence | ||||||||||
| Hull weight | 500 | 226.80 | Glen-L Marine Designs - Hot Rod Specifications | ||||||||||
| Hull hardware | |||||||||||||
| Engine | 535 | 242.68 | Bare engine weight. Handbook of Engine Swapping, John Thawley, 1960 | ||||||||||
| Gross Load | 1301 | 590.00 | Calculated (See Step 5). | ||||||||||
| Person Capacity | 4 | 660 | 299.38 | Maximum person capacity = 165 lbs per person | |||||||||
| LWL | 1738 | 788.36 | Loaded Water Line. Glen-L Marine Designs - Plans Sheet # 1 | ||||||||||
| Deck weight | 40 | 18.14 | Estimated | ||||||||||
| Deck hardware | |||||||||||||
| Frames | 180 | 81.65 | Glen-L Marine Designs - frame kit shipping weight | ||||||||||
| Engine weight | 800 | 362.88 | Weight of engine and related parts. Includes engine, driveline and battery. | ||||||||||
| DFSP at 11" WL | 1738 | 0.77 | Dfsp | Displacement to Float Plane (m3) at 11" waterline - Hullform95 | |||||||||
| DFSP at 16" WL | 6667 | 2.95 | Dfsp | Displacement to Float Plane (m3) at 16" waterline - Hullform95 | |||||||||
| Complete Boat build photos can be seen at : | http://www.boats.chelseacoachworks.com | ||||||||||||
| (c) | Swamped Weight of vessel and fittings other than engine-related equipment | ||||||||||||
| Formula : | |||||||||||||
| Ws = sum ( Wh * k ) + Wd + 0.69 Wf | |||||||||||||
| Where : | |||||||||||||
| Ws = | Swamped weight (kg.) | ||||||||||||
| Wh = | Dry weight in kilograms of various materials used in hull construction (kg.) | ||||||||||||
| k = | Conversion factor applied to the weight of each piece of hull material (Wh), to convert the dry material (h) to an equivalent weight when submerged in fresh water as determined byTable 4-2 . | ||||||||||||
| Wd = | Weight of deck and superstructure (kg.) | ||||||||||||
| Wf = | Weight of permanent fittings not included in Wd (kg.). | ||||||||||||
| Step 1 | Identify the hull construction components and determine their weights when submerged, sum( Wh * k ) | ||||||||||||
| Part Description | Weight (lbs) | Weight (kg) | Factor(K) Table 4-2 | Submerged Weight | |||||||||
| (lbs) | (kg) | ||||||||||||
| sum(Wh x k) = | Weight of hull frames | 180.00 | 81.65 | * | -0.96 | = | -172.80 | -78.38 | |||||
| Lumber & Plywood | 301.70 | 136.85 | * | -0.96 | = | -289.63 | -131.38 | ||||||
| Fiberglass | 18.30 | 8.30 | * | 0.33 | = | 6.04 | 2.74 | ||||||
| Hull bronze hardware | 2.00 | 0.91 | * | 0.89 | = | 1.78 | 0.81 | ||||||
| Hull steel hardware | 8.00 | 3.63 | * | 0.88 | = | 7.04 | 3.19 | ||||||
| TOTAL | 510.00 | 231.34 | -447.57 | -75.19 | |||||||||
| Wh = | Dry weight in kilograms of various materials used in hull construction (kg.) | ||||||||||||
| k = | Conversion factor applied to the weight of each piece of hull material (Wh), to convert the dry material (h) to an equivalent weight when submerged in fresh water as determined byTable 4-2 . | ||||||||||||
| To obtain the factor for materials not listed in Table 4-2, the following formula may be used : | |||||||||||||
| Factor = ( Specific Gravity - 1 ) / Specific Gravity. | |||||||||||||
| Note : The Specific Gravity is the ratio of the density of a substance to the density of water (fresh) at 39 degrees F. Weight of water (fresh) at 39 degrees F = 62.4 lbs/cubic foot. Its Specific Gravity is 1.0 . | |||||||||||||
| Notes : | Fiberglass cloth = 176 sq. ft of 7.5 oz. cloth at .104 lbs/sq.ft . (Fiberglass Boatbuilding for Amateurs, Ken Hankinson, 1982) | ||||||||||||
| Step 2 | Identify the deck construction components and determine their dry weights Wd | ||||||||||||
| Part Description | Weight (lbs) | Weight (kg) | |||||||||||
| Wd = | Lumber & Plywood | 39.00 | 17.69 | ||||||||||
| Fiberglass | 1.00 | 0.45 | |||||||||||
| TOTAL | 40.00 | 18.14 | |||||||||||
| Step 3 | Identify the weight of permanent fittings not included in Wd (e.g. factory installed equipment). | ||||||||||||
| Part Description | Weight (lbs) | Weight (kg) | |||||||||||
| Wf = | 0.00 | 0.00 | |||||||||||
| TOTAL | 0.00 | 0.00 | |||||||||||
| Step 4 | Identify the engine and related equipment and calculate their weight We as installed. Includes engine, driveline and battery. | ||||||||||||
| Part Description | Weight (lbs) | Weight (kg) | |||||||||||
| We = | Engine. Chevrolet 283 CID V8. | 535.00 | 242.68 | ||||||||||
| Bellhousing | 10.50 | 4.76 | |||||||||||
| Velvet Drive 71C Transmission, brackets and power takeoff adapter | 117.50 | 53.30 | |||||||||||
| H Joint | 6.00 | 2.72 | |||||||||||
| V-Drive Takeoff | 5.00 | 2.27 | |||||||||||
| V-Drive | 50.00 | 22.68 | |||||||||||
| Battery | 44.00 | 19.96 | |||||||||||
| Fuel tanks and 15 gallons @ 6.2 lbs. / gallon | 111.60 | 50.62 | |||||||||||
| Glenwood manifolds and 35 degree elbows - aluminum | 26.00 | 11.79 | |||||||||||
| TOTAL | 905.60 | 410.78 | |||||||||||
| Step 5 | Calculate Gross Load. (DFSP at 16" WL) | ||||||||||||
| GL = | ( | Dfsp | * | 1000.00 | ) | / | 5 | ||||||
| ( | 2.95 | * | 1000.00 | ) | / | 5 | |||||||
| 2950.00 | / | 5 | |||||||||||
| 590.00 | kg | 1300.95 | lbs. | ||||||||||
| Where : | |||||||||||||
| GL = | Recommended maximum gross load in kilograms. | ||||||||||||
| Dsfp = | Displacement to static float plane (kg) (DFSP at 16" WL) | ||||||||||||
| Step 6 | Calculate the maximum number of persons. | ||||||||||||
| Max number of persons = | GL | / | 75 | ||||||||||
| = | 590.00 | / | 75 | ||||||||||
| = | 8 | ||||||||||||
| Step 7 | Determine the swamped weight of the vessel by substituting previously calculated terms in the formula. | ||||||||||||
| Ws = | [ Wh * k ] | + | Wd | + | 0.69Wf | ||||||||
| = | -75.19 | + | 18.14 | + | 0.00 | ||||||||
| = | -57.04 | kg | -125.78 | lbs. | |||||||||
| Where : | |||||||||||||
| Ws = | Swamped weight (kg.) | ||||||||||||
| [ Wh * k ] = | Submerged weight of various materials used in hull construction (kg.) as calculated in Step 1. | ||||||||||||
| Wd = | Weight of deck and superstructure (kg.) as calculated in Step 2. | ||||||||||||
| Wf = | Weight of permanent fittings not included in Wd (kg.) as calculated in Step 3. | ||||||||||||
| Step 8 | Calculate the amount of flotation required Wfl . | ||||||||||||
| Wfl = | Ws | + | 0.75We | + | 0.25Wl | ||||||||
| = | -57.04 | + | 0.75 * | 410.78 | + | 0.25 * | 590.00 | ||||||
| = | -57.04 | + | 308.09 | + | 147.50 | ||||||||
| = | 398.54 | kg | 878.78 | lbs | |||||||||
| Where : | |||||||||||||
| Wfl = | Amount of flotation required. | ||||||||||||
| Ws = | Swamped weight in likograms (calculated in Step 6). | ||||||||||||
| We = | Dry installed weight of the propulsion system, plus the dry weight of the battery(s) (calculated in Step 4). | ||||||||||||
| Wl = | The maximum
gross load in kilograms, less the dry installed weight of the propulsion
system and the dry weight of the battery(s) |
||||||||||||
| Step 9 | Calculate the required volume of buoyant material Vb | ||||||||||||
| Vb = | Wfl | / | ( | 1000 | - | 1.05 * Wb | ) | ||||||
| = | 398.54 | / | ( | 1000.00 | - | 33.75 | ) | ||||||
| = | 398.54 | / | 966.25 | ||||||||||
| = | 0.41246 | m3 | 13.26 | ft3 | |||||||||
| Where : | |||||||||||||
| Vb = | Volume of buoyant material (kg.) | ||||||||||||
| Wfl = | Amount of flotation as calculated in Step 8. | ||||||||||||
| 1000 = | The factor representing a weight (kg.) of 1 m3 of fresh water. | ||||||||||||
| Wb = | Weight (kg.) of 1 m3 of buoyant material used. Assuming use of polyurethane foam of 2 lbs. / ft3. ( 32.14 kg / m3 ) | ||||||||||||
| References | |||||||||||||
| (1) | Construction Standards For Small Vessels, 2010 EditionTP 1332E (04/2010 | ||||||||||||
| http://www.tc.gc.ca/Publications/en/TP1332/PDF/HR/TP1332E.pdf | |||||||||||||
| Prepared by Paul Kane, Chelsea Quebec, Canada Revised 11-JAN-2012 | |||||||||||||
| Phone : | (819) 827-3701 | ||||||||||||
| Email : | paulkane@chelseacoachworks.com | ||||||||||||
| Building the Glen-L Hot Rod : | http://www.boats.chelseacoachworks.com | ||||||||||||