Max HP Rating for a 1980 Swiftcraft Seagull?

[cala90]

Hey guys,

Just wondering if anyone could help me out. I've got a 1980 Swiftcraft Seagull with a 1977 Johnson 140hp on the back. I was wondering if anyone knew what the maximum HP rating for these boats are? After reading a few posts I'm a bit worried about the insurance side of things!

Cheers!

[Chimo]

Cala90

That would fly given the shape of the bottom of those things. I had a Swiftcraft Falcon (15ft ish) and that was rated to 100HP so the Seagull being a bit heavier with the cabin and a little longer, I think; would probably be close to the 140 HP.

Cheers
Chimo

[ozynorts]

Also what is the weight of the old donk? A new one would probably have to about the same.

[Noelm]

back in those days, there was no recomended HP or load rating, you just fended for yourself, so with that being said, I guess there must be some process to have an old boat assessed to attach some sort of compliance plate, though I have never come across any that have been done.

[cala90]

Thanks for the replies!! I've checked the manufacturers plate and for some reason there is no number next to max HP or max load (people). I called my insurance company and explained the situation and was told that if the engine does not exceed 40knots i will be covered. I'm not sure what the max speed a 140hp would go on a 16ft boat! (No speedo in the boat doesn't help haha)
my guess would be to call Johnson and ask them to be sure?? Any other advice?

[davo]

I disagree with the idea of no recommended HP ratings in the old days. Boats like the Swiftcraft Seagulls and Savage Pacific's etc... all had name plates with specifications on them. 140HP is quite high for one of these. Typical power was 70 - 115 HP range. I know our old Savage Pacific did 40 Miles per hour with an 85 HP Merc. Keep looking for information, there are plenty of these boats still operating down South.

[cala90]

I disagree with the idea of no recommended HP ratings in the old days. Boats like the Swiftcraft Seagulls and Savage Pacific's etc... all had name plates with specifications on them. 140HP is quite high for one of these. Typical power was 70 - 115 HP range. I know our old Savage Pacific did 40 Miles per hour with an 85 HP Merc. Keep looking for information, there are plenty of these boats still operating down South.

Thanks davo! Just wish the name plate had something written on it! I'll keep an eye out!

Cheers

[Excalibur29]

Hi,
I have a 1976 swiftcraft seagull with a 79 model 115hp Evinrude.
I have had it from new.
They were rated for up to 120HP (40 HP minimum recommended)
I have calulate their Maximun HP using AS1799-1 and get 73kW rounded up to (75kW per AS standard) resulting in 100.5 HP.

Formula is from table 2.2 of AS1799-1 boat type with remote steering 500mm transom height.
Power capacity kW [(16 x factor) -67] increased to next multiple of 5
Factor is calulated by (hull boat length in metres x transom width at water level)
factor 5 x 1.75 = 8.75

[(16 x 8.75) - 67] = 73 (use 75)

To convert to HP x by 1.34 75 x 1.34 = 100.5 HP

[cormorant]

That motor is rated in old hp not new HP as well so .............. at the prop or at the flywheel. You are not getting a full modern 140 anyway.

[dnej]

So 140 then would be what today, 120hp at the prop?
David