1970 20' potter - rebuild max engine weight

[Gaud]

i am finishing up my 20' sea craft and now have to re power it.

I re did the transom and raised it to 25". I did NOT raise the floor.

what would you guys suggest as the max weight to have back there?

i am considering the mercury 150hp 4 stroke which is the lightest in its class.

a few friends are trying to convince me to go with a bigger 200 2 stroke.

thoughts?

thank you!!!

[caper]

400 lbs.

[Old'sCool]

BRP's new 150 is light also.

[SailorChlud]

Ditto on the 400 pounds. My 115hp 2 stroke weighs 363lbs. Add two batteries and an oil tank in the stern, we are a tad over. With just my weight in the stern, the water rises to just above the scuppers. Hell, with "only" the 115hp, my 1972 20' Seafari does 35mph. A 150hp should be the absolute max anyone can use safely in any sea conditions other than dead calm.

[Bushwacker]

Originally Posted by Gaud

. . . a few friends are trying to convince me to go with a bigger 200 2 stroke.

thoughts?

thank you!!!

Your friends obviously don’t realize how efficient the 20’ SeaCraft hull design is!

It’s basically the same hull as the 19’ bowrider, which was designed in the early 60’s when the biggest motors were the I-6 Merc and V-4 OMC 2-strokes that weighed less than 300 lbs and weren’t much more than 100 hp, rated at the crank, not the prop like today! So it doesn’t need as much power as modern hulls with more beam and heavier less efficient construction. Many were sold new with 85 hp motors and ran fine with those light motors. Terry England’s modified bowrider handles 4 fully equipped divers and 8 tanks with a light 90 hp E-Tec with no problems.

Power selection also depends on how and where you intend to use the boat. If you’re on flat inland rivers and lakes where you can run 50+ mph, a big 2-stroke is fine. Although the 20 SeaCraft hull is very stiff because if it’s large stringers and balsa core decks, it’s relatively light, so if you intend to run offshore, it doesn’t need a lot of power. You’ll find that it will start to go airborne at about 20 kts once seas get up to about 3’. If you intend to run in those conditions, the added weight, expense and poorer ride and low speed planing associated with a big heavy motor doesn’t make a lot of sense to me!

[wattaway2]

Having had a 20 sf with both a 225 and 200 ocean pro on it — alot of fun by the way . I truthfully say it would have been a better boat with a 140 to 150 on the back or a very light 175