The Ownership Playbook
Most $2,000,000 houses ask you to choose: a vacation place, a home, or an investment. This one holds nine income units and a thirteen-slip marina on a single deed — so the same purchase runs four entirely different ways. Pick the one that fits your life. Change your mind later.
Rents and slip income below are owner-reported, August 2026 · buyer to verify
What one deed holds
Every scenario on this page is built from the same pieces. Here they are — with what each earns today, as reported by the owner.
Inside the main house · $6,000/mo
| Owner's residence — the entire first floor | Yours |
| First-floor studio | $1,200 |
| Upstairs suite — L-shaped, full bath | $1,500 |
| Upstairs suite — full bath & kitchenette | $1,200 |
| Upstairs suite — full bath & kitchenette | $1,100 |
| Upstairs suite — full bath & kitchenette | $1,000 |
The owner notes every upstairs suite is below the going studio rate — market is $1,200+ — so the inside rents carry built-in upside.
Outside your doors · $90,000/yr
| Waterside cottage | $1,500 |
| Attached cottage | $1,500 |
| Apartment above the garage | $1,000 |
| The marina — 13 slips & winter storage | ±$42,000/yr |
These four never touch your front door or your stairs. They are the income that survives every privacy decision you could make.
Everything running, as it runs today
$162,000/yr
$10,000 a month across nine rented units, plus roughly $42,000 from the marina — while the entire owner's first floor stays yours.
The four plays
Each illustration compares owner-reported gross income against a monthly carry of ±$14,400 — 25% down on $2,000,000, 30-year fixed at prevailing jumbo rates, taxes at the assessed $37,559 and insurance estimated. Like any property, this one carries operating costs — maintenance, utilities, vacancy, grounds and dock reserves — which are not deducted below, and are not deducted from the comparison houses either. Get your own financing and insurance quotes, and verify everything.
Scenario one
Take the whole main house private — all seven bedrooms, both floors, one family, nobody on your stairs. The two cottages, the garage apartment and the marina keep earning about $90,000 a year without ever touching your front door.
Here is what that actually means. At 25% down, principal, interest, taxes and insurance run about $14,400 a month, and the income covers $7,500 of it. Net, roughly $6,900 a month — against $9,237 to carry a $1.3 million Bay Shore waterfront house that has no cottages, no income and no marina.
Read that again. The seven-bedroom compound with thirteen slips costs roughly $2,300 a month less than a house priced $700,000 below it. Bring the outside rents and the slips to market and the gap widens to more than $3,500 a month.
Illustrative and not guaranteed. Comparison figures are ours, taxes and insurance on the comparison house are estimated, and rates move. The interior suites are currently tenanted at will; clearing them is a normal New York notice process a buyer should plan into the first months of ownership.
Scenario two
Keep everything exactly as it runs today. You occupy the entire first floor — living room, dining room, kitchen, French doors to the pool and the water — while nine units and thirteen slips gross about $13,500 a month against a ±$14,400 carry.
The arithmetic is blunt. Under a thousand dollars a month separates the income from the mortgage, the taxes and the insurance — to live on 180 feet of South Shore waterfront with a pool, a hot tub and your own marina. And because every upstairs suite sits below the going studio rate for the area, that gap closes the first time a lease turns over.
Scenario three
Don't live here at all. The owner's floor rents at roughly $3,500–4,000 unfurnished, lifting the property to about $204,000 gross across ten units and the marina — roughly $17,000 a month against a $14,400 carry. Stated plainly, because a serious buyer will run it in week one: once operating costs are applied this is a low-single-digit capitalization rate, so the case here is not yield. It rests on three things a cap rate doesn't capture.
Consolidation. Assembling this rent roll the ordinary way means three separate houses, three closings, three tax bills, three roofs. Here it is one deed. Scarcity. Thirteen slips currently let at roughly $3,200 each against a coastal market running several times that — and new slips are effectively unpermittable between the Army Corps, NYSDEC tidal wetlands and Islip's residential dock cap. What exists here cannot be rebuilt. Basis. Unusually much of the value sits in land improvements — bulkhead, docks, pilings, pool, outdoor kitchen, site electric — rather than the 1902 structure. Have your CPA model a cost segregation study against your own situation; nothing here is tax advice.
Buyers should plan on a substantial cash position: in-place income supports materially less debt than a conventional loan-to-value would suggest. The rent roll, slip roster and permit file are open to qualified buyers.
Scenario four
The compound is private from September to June — then the main house lets furnished for the summer on monthly terms, at a premium, while you take the boat to Fire Island or hand the season to a family who'll pay for it. Note the local rule, stated plainly: the Town of Islip requires stays of fourteen nights or longer — this is a monthly-rental play, not a nightly one, and the numbers here respect that.
Two more moves for the buyer thinking in years: the flat roof over the main house carries a contractor-quoted plan for an ±860 sq ft primary suite — a private owner's floor upstairs that would free the entire first floor to earn year-round. And a slip owner's trick from the current owner himself: keep one slip, rent a boat for the summer, and skip ownership entirely.
Side by side
| The play | You occupy | Gross income | vs ±$15K carry |
|---|---|---|---|
| Private compound, all 7 bedrooms | Entire main house | ±$7,500/mo | ±$6,900/mo net |
| Personal house, as it runs | The full first floor | ±$13,500/mo | ±$950/mo net |
| Pure investment | Nothing — it all earns | ±$17,000/mo | income clears the carry |
| Seasonal hybrid | Main house, Sept–June | ±$10–12K/mo | ±$2,400–4,400/mo net |
The comparison that matters
| Bay Shore waterfront | Price | Net monthly |
|---|---|---|
| 64 Mowbray — 7BR, 180 ft, pool, 13-slip marina | $2,000,000 | $6,943 |
| A house at $1.3M — no cottages, no income, no marina | $1,300,000 | $9,237 |
| A house at $1.5M — no cottages, no income, no marina | $1,500,000 | $10,568 |
| A house at $1.75M — no cottages, no income, no marina | $1,750,000 | $12,232 |
All at 25% down, 30-year fixed, 7.00%, principal and interest plus taxes and insurance. Operating costs are excluded from every row alike. The compound is the only line on this table that earns while you live in it.
All figures illustrative and not guaranteed. Income is owner-reported (August 2026) and approximate; buyer to verify. Figures are gross and are shown before operating expenses — maintenance, utilities, vacancy, grounds and dock reserves apply here as they do to any property, and are excluded from the comparison houses on the same basis. Carry assumes 25% down on $2,000,000, 30-year fixed at 7.00%, taxes of $37,559/yr and estimated insurance; comparison-house taxes and insurance are estimated. Rates and insurance quotes vary — obtain your own. Multi-family use, permitted unit count and rental permitting to be independently verified by buyer with the Town of Islip. Rentals under 14 nights are not permitted on the Islip mainland. Not legal, tax or investment advice.