When two boats share the same hull type — in this case both the ElectraCraft Lapstrake Series 18LS 2010 and the ElectraCraft Lapstrake Series 21LS 2009 are modified vee designs with fiberglass construction — the buying decision usually comes down to a handful of practical questions: how many people are you putting on the water, how far do you trailer, and what does your tow vehicle weigh?
On paper these two are close siblings in the size department — ElectraCraft Lapstrake Series 18LS 2010 at 18,0 ft versus ElectraCraft Lapstrake Series 21LS 2009 at 21,0 ft. At 21 lbs and 31 lbs respectively, both sit in a similar weight class — either should pair comfortably with most mid-size SUVs and half-ton trucks, though always confirm your specific tow rating with the motor added.
For family outings this is probably the sharpest distinction between the two. The ElectraCraft Lapstrake Series 21LS 2009 is rated for 12 passengers, while the ElectraCraft Lapstrake Series 18LS 2010 caps at 9. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the ElectraCraft Lapstrake Series 21LS 2009 could be the deciding factor.
Bottom line: Choose the ElectraCraft Lapstrake Series 21LS 2009 if your priority is putting more people on the water — it handles 12 passengers and at 21,0 ft it has the deck room to back that rating up comfortably. The ElectraCraft Lapstrake Series 18LS 2010 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 9 that costs less to run day-to-day.