Outboard sizing

[swhalliday]

I am building a P19 in Australia.

The boat and trailer will cost about $8k, however a 90 hp outboard (recommended) will cost close to $16k fitted with gauges, looms etc.

Can I get by with say a 60 or 70 hp, which are much cheaper ?

It would be great if we had a table of different horsepower with speeds at different revs for each, e.g. a 70 hp will give 25 knots at 4000 revs, and 18 knots at cruising revs.

Guess I will need to look for low hours second hand engines.

[jacquesmm]

It all depends on the weight of the boat. If she is very light and with 2 persons on board, she will plane (17 knots) with a 50 HP but the engine will have to run at high rpm most of the time.
I can give you a range of speeds in function of the weight and HP but do not blindly trust the nominal HP of an engine.

I would try to find a 90 HP in your budget.

[BarraMan]

The last thing you want is an underpowered boat - trust me! You will be disappointed with your build if you don’t give it the power to shine!

[fallguy1000]

I am building a P19 in Australia.

The boat and trailer will cost about $8k, however a 90 hp outboard (recommended) will cost close to $16k fitted with gauges, looms etc.

Can I get by with say a 60 or 70 hp, which are much cheaper ?

It would be great if we had a table of different horsepower with speeds at different revs for each, e.g. a 70 hp will give 25 knots at 4000 revs, and 18 knots at cruising revs.

Guess I will need to look for low hours second hand engines.

Where you gonna use her and typical runs? The yamaha F70 is an engineering marvel for power to weight, but I am with Barraman. Power is needed if you run 20 miles.

[cape man]

Can I get by with say a 60 or 70 hp, which are much cheaper ?

You will get by, but slowly

That is a big boat for a 90.

[Dr. Pete]

I would so appreciate some input on this. Getting closer to splash on XF20. Probably runs on the heavy side for the boat. 8 ft of front deck. 27 gallon fuel tank on that end. 9 ft of sole with smaller center console and back less than 4 ft decked. Novice builder so have exceeded glass and epoxy expectations. 90 make it move or need more? I don’t have plans on long runs. Fishing only the bay at Port Aransas. Not got plans for time trials or any timed events. Thanks

[Aripeka Angler]

I would so appreciate some input on this. Getting closer to splash on XF20. Probably runs on the heavy side for the boat. 8 ft of front deck. 27 gallon fuel tank on that end. 9 ft of sole with smaller center console and back less than 4 ft decked. Novice builder so have exceeded glass and epoxy expectations. 90 make it move or need more? I don’t have plans on long runs. Fishing only the bay at Port Aransas. Not got plans for time trials or any timed events. Thanks

Doc, a 90hp motor is more than adequate for your boat.
My XF20 performs great with a 70.
Hard to imagine your boat being much heavier than my Red Alert...

[Dr. Pete]

Thanks Richard. Don’t want too little or too much. Just enough is just enough. Got some advice today from Guy P and I’m on go to buckle the sole in to make some waves! Couple days of rainy weather coming up. Outside build theses days. Looking forward to some progress. Thanks all!

[Aripeka Angler]

Doc,
Send some of your rain our way, our cows are suffering from our seasonal drought.
If I were to re-power right now, I’d go with the Yamaha or Etec 90.

[CatfishHunter]

doc that 90 will be more then enough, i'm plenty happy with my merc 60 bigfoot. it spins the same prop as the 90/115, but a few lbs lighter. i think anything larger would be over kill