Boat weight
Printed From: The Fishing Website
Category: General Forums
Forum Name: The Boat Shed
Forum Description: Discuss all things boating.
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=135295
Printed Date: 03 Jun 2026 at 6:52am
Topic: Boat weight
Posted By: C Pick
Subject: Boat weight
Date Posted: 25 Mar 2021 at 7:41pm
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I finally decided to do a small rust repair on my trailer after being scolded by the WOF dude at the last two checks. As these things do, it has degenerated into stripping the trailer back to the chassis for a new set of rollers and a complete new suspension setup... I know I should have put the boat and trailer over a weighbridge before going down this road but I never intended to replace the suspension before putting the boat on blocks and taking the trailer apart. I'm now trying to work out what weight rated leaf springs to buy. My question is, does anyone want to hazard a guess at what a 6.5m alloy HT would weigh? It has a 170L fuel tank and a 250hp etec on the back. It's not a brand name boat and is built fairly sturdily, I'm guessing it was built as a commercial boat, perhaps for paua.... |
Replies:
Posted By: smudge
Date Posted: 25 Mar 2021 at 7:45pm
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Hazard a guess alright. My guess is at least 2 tonne. But really that's just a guess to keep this conversation alive. Reckon I won't be too far off though. What is the hull? ------------- Best gurnard fisherman in my street |
Posted By: C Pick
Date Posted: 25 Mar 2021 at 7:53pm
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Posted By: C Pick
Date Posted: 25 Mar 2021 at 7:54pm
| My guess is that it's a pelin design of some kind? |
Posted By: smudge
Date Posted: 25 Mar 2021 at 8:02pm
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Wow, that is a nice looking ship. Easy 2 tonne
------------- Best gurnard fisherman in my street |
Posted By: C Pick
Date Posted: 25 Mar 2021 at 8:18pm
| Cheers mate! |
Posted By: OneWayTraffic
Date Posted: 25 Mar 2021 at 9:07pm
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McLay 651 Crossover with 5mm bottom and 4mm sides: 1000kg hull only. Stabicraft 6.8m ultracab 1485kg dry hull. Extreme Game king 6.45m 1800kg boat trailer motor I wouldn't dice with under 2000kg either. You could go a little higher at the expense of a rougher ride on the hull.
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Posted By: C Pick
Date Posted: 25 Mar 2021 at 9:21pm
| Cheers mate. I ordered 2000kg springs but was wondering if I had gone too light. I had planned on 2500kg springs but the trailer outfit had no galvanised ones |
Posted By: smudge
Date Posted: 25 Mar 2021 at 9:42pm
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2000 to 2500 has to be ball park I would imagine
------------- Best gurnard fisherman in my street |
Posted By: OneWayTraffic
Date Posted: 25 Mar 2021 at 11:53pm
| Put it on a weighbridge after it's back on the road and then you'll know. Boats tend to get heavier over time as the temptation is to add stuff. Don't forget that you can ignore axle, tire and towball weight. |
Posted By: Steps
Date Posted: 26 Mar 2021 at 9:21am
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What hp on the back and what is your top speed at best trim for that speed? From that we can calculate the total gross weight of the boat on the water.. From my data base which is primarily glass and alloy boats most upto 7m. 6 to 6.5m generally fall between 1800 and 2200 kg.. then take off the weight of the people Now add the weight of the trailer, have to make this a real guess, say 450 kg So as a all up guesstimate, not knowing your WoT speed I would be going for at least 2500kg |
Posted By: C Pick
Date Posted: 26 Mar 2021 at 11:30am
| It's an etec 250HO. WOT is 85kph |
Posted By: Steps
Date Posted: 27 Mar 2021 at 4:00pm
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I dont know how accurate those numbers are. And only estimating the hull constant coefficient to guesstimate similar hulls 52 mph is scarry fast.. will be up near or will be chine walking Total gross weight (people gear fuel, the packed lunch..) on water comes out around 1950.. 2020 A 635 buccaneer 4 adults etc 200hp hits around 48 mph .. that comes in at around 1650/ 1700 kg. |
Posted By: C Pick
Date Posted: 27 Mar 2021 at 5:38pm
It's definitely over-engined but I prefer that to the other way around. 46kts according to the plotter
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Posted By: OneWayTraffic
Date Posted: 27 Mar 2021 at 8:57pm
| It doesn't matter at the moment anyway. Weigh it once the wheels are on. If you are over you'll need to bite the bullet anyway. If not then all good. |
Posted By: Big -Dave
Date Posted: 27 Mar 2021 at 10:03pm
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I'd be going 2500kg, at that weight, the springs being so short, they are virtually solid. What are you doing with the suspension?, going for a rocker type?, they ride a lot smoother. ------------- you can't fix an idiot with duct tape, but it does muffle them for a while... |
Posted By: Steps
Date Posted: 28 Mar 2021 at 9:59am
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I would go the 2500kg Espec with Daves post above. Dave is pretty experienced, hands on, on to it guy.. It's definitely over-engined but I prefer that to the other way around. Totally agree.. And has nothing to do with how fast you can go . Thu it is nice to have the ability to cruise comfortable at higher speeds far more economically than if do so at min or well powered. Its better to have that power there if need. for some many reasons. That wave climbs in front, or get caught on the beam.. Then the everyday stuff.. better economy , espec with a bit chop and have to throttle back because the hull performs under power so much better. Just set throttle and go. I was a min power 115 on 1250kg gross weight on water hull. Good performer, 130/140 being the ideal. Eventually found a 150. Down side.. throttle bit more sensitive, bit more careful on take off... which makes a skipper bit more aware of what is going on around, inside and outside the hull. |
Posted By: C Pick
Date Posted: 28 Mar 2021 at 10:18am
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Cheers guys I'll go for the 2500kg springs. I've only gone WOT a couple of times, once to test max revs and once in a drag race with a mate. **** happens too quickly at that speed... The boat used to have a pair of Honda 90's up to the start of last year. It dragged its bum and never felt right unless it was being wrung out. With the new engine it has less weight on the back, only one leg dragging in the water and more ponies when needed. The upshot is I used to be able to get 1.2km/L at best at 23kts, now I get 1.6km/L at 30kts. The boat sits better in the water and handles far better, it's gone from being an underpowered slug to the boat it always should have been. |
Posted By: Steps
Date Posted: 29 Mar 2021 at 8:23am
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Its good to see the occasional hands on real life posts of where a person does a repower.. forget 2S or 4S.. just hp at the prop.. from say a min power to good power plus. There are so many armchair poo pooers who scoff, even to the extent of being 'aggressive' in the benefits of well powered plus. I used to be able to get 1.2km/L at best at 23kts, now I get 1.6km/L at 30kts. An ave cruise of 32 mph with the 150hp I get around 1mile (1.6km) per L.. A 150hp fast cruise around 38 mph 3900rpms Im about the same as the 115 3950 @ 32 mph 0.8 miles/ L |