A practical Gili dive boat layout starts with clear guest flow: cylinders racked on centreline or gunwale benches, compressor isolated from the passenger area, wide side or stern entries, robust ladders clear of propellers, shaded seating, and dedicated wet zones for cameras and rinse tanks. Every decision protects diver safety, shortens turnarounds and keeps noise and heat away from guests.
Operational realities for Gili dive operators
Designing a dive boat for the Gili islands is not abstract naval architecture. It is about running two or three daily trips from Gili Trawangan, Gili Air or Gili Meno in mixed sea states, loading from beaches or jetties, and turning the boat around quickly between dives.
Common constraints we design around include:
- Short transit legs (10–45 minutes) but frequent daily cycles.
- High-frequency boarding on crowded beaches and shared jetties.
- Heavy cylinder handling in swell by crews of varying experience.
- Need to separate dive operations from snorkel and fun-trip usage.
These constraints drive decisions on tank rack locations, compressor siting, ladder placement and shaded space. A good dive boat builder lombok project starts from the actual operating plan, not a catalogue drawing.
Tank rack layout and securing systems
Cylinder storage and use define the working deck. Poor rack placement creates trip hazards, sore backs and long changeover times. We usually consider three primary rack geometries on timber or composite hulls in the 12–25 m range.
Centreline island racks
Centreline island racks run along the longitudinal axis, often with back-to-back seating. Advantages:
- Balanced weight distribution, reducing list as cylinders empty.
- Clear side decks for entry, exit and crew movement.
- Simpler segregation between “wet” outer zone and “dry” inner zone.
We design the base to take point loads from full 12–15 L steel or aluminium cylinders, with tied-in transverse frames or through-bolted plates on composite decks.
Gunwale bench racks
Gunwale racks integrate tanks into side benches. This suits narrower hulls or boats sharing duty as transfer vessels. The benefits are:
- Low reach distance from seated diver to water entry.
- Short carry path from ladder to bench during recovery.
The penalty is a narrower clear walkway. We counter this by careful spacing, staggered seating and specifying non-slip sole finishes along the centre route.
Securing and changeover efficiency
For Gili operations, cylinders are loaded and unloaded daily. We avoid complicated, fatigue-prone securing methods. Typical options:
- Webbing or bungee loops with stainless eyes at two heights per tank.
- Moulded or timber saddles with chocks to prevent rolling.
- Quick-change top clips that can be operated with gloved hands.
We plan enough spacing so BCs can remain on cylinders between dives, reducing on-board lifting. On the drawing board we allocate a realistic cylinder count per trip, plus 10–20% buffer for guides and safety reserve.
Compressor location, noise and heat management
Onboard compressors can transform Gili operations, but they introduce weight, heat, noise and vibration. Location is never an afterthought; we plan it together with structural loads, ventilation and exhaust routing.
Below-deck versus deck-mounted compressors
Where hull depth allows, a partially enclosed, below-deck compressor room has advantages in noise control and security. However, it must be:
- Accessible for routine maintenance with full filter-change clearance.
- Cross-ventilated to avoid heat build-up affecting fill rates.
- Fitted with secure bottle brackets for storage banks, if used.
On shallower boats, a deck-mounted unit under an awning or hardtop extension may be preferable. We then use sound-damping panels and non-combustible heat-shielding around exhausts and hot lines.
Noise, vibration and guest comfort
Even a well-maintained compressor will dominate the soundscape if poorly sited. To preserve briefing audibility and guest comfort, we usually:
- Mount the unit aft, separated from the main seating cluster.
- Use resilient mounts and structural reinforcement below the skid.
- Route intake air away from engine exhaust and boat fumes.
This allows filling during transits without overwhelming conversation. Where shore-based filling remains primary, we still reserve space and scantling capacity so a compressor can be retrofitted later.
Entry, exit and ladder design
Gili dive sites range from sheltered slopes to current-prone corners. Divers and guides need predictable, uncluttered entry and robust, wide ladders to exit in variable swell.
Entry points: side versus stern
Side entries near the midship section minimise roll as groups enter and encourage shorter swims to the bow or stern ladders. Stern platforms, where hull form permits, give a very intuitive water access path.
We typically include:
- Soft non-slip deck surfaces at all entry points.
- Handholds and grab rails to assist kitting-up and controlled steps.
- Clear zones free from hoses, fins and loose equipment.
The chosen pattern is mapped against the launch site. Boats boarding from Bangsal, Teluk Nara or beach landings may need different freeboard-to-water solutions.
Ladder placement and geometry
Ladder design is a safety-critical detail. For Gili operations we pay attention to:
- Position: always clear of propellers and steering gear swing arcs.
- Depth: at least three rungs below the water surface for fin-on climbing.
- Width: enough clearance for a diver wearing a BC and cylinder.
- Standoff: angled so fins do not press against the hull when climbing.
We reinforce hull plating or timber transoms where ladders attach, preventing local crushing from repeated dynamic loads. Handholds continue above deck height so divers can stand securely before removing fins.
Camera tables, rinse tanks and equipment zoning
Underwater photography is common on Gili trips, from compact cameras to larger housings. Cameras, masks and regulators need protected, non-slip surfaces and clean rinse water.
Dedicated camera tables
A small, raised camera table with a coaming lip, non-slip mat and shaded position near the helm or midships pays dividends. We separate this from general equipment benches to avoid sunscreen, drinks and sand contaminating seals and ports.
Power points, if fitted, must be clearly labelled, drip-protected and wired to marine standards. We generally discourage charging during crossings unless the operator has strict procedures.
Rinse tanks and wet equipment areas
Rinse tanks need volume rather than depth, with rounded internal corners and smooth surfaces that will not abrade gear. We often integrate:
- One tank for cameras only, located adjacent to the camera table.
- One or more general gear rinse bins aft, away from the dry seating zone.
Drainage paths must lead overboard without pooling on deck. Scuppers are sized for real-world conditions: multiple divers moving, hoses filling tanks and occasional heavy rain.
Shade, seating and diver flow
Shade is not a luxury in the Lombok and Gili sun; it is a fatigue and dehydration control measure. We combine rigid tops, canvas extensions and removable panels to create protection while managing windage.
Planning the flow on two-tank days
Two-tank schedules need a clear process from boarding to final disembarkation. We sketch diver flow as a loop:
- Boarding point and initial stowage of bags and personal items.
- Briefing area with good sightlines and low noise.
- Kitting-up zone near racks with handholds.
- Entry line to side or stern, avoiding cross-traffic.
- Recovery ladder route back to benches for de-kitting.
We keep toilets, refreshments and dry storage on a parallel but separate path so non-diving movements do not cut across divers in full kit.
Seating ergonomics and under-bench storage
Bench heights, backrests and foot clearance matter over multiple trips. We dimension:
- Seat height to minimise strain when standing with a cylinder.
- Back support where possible for surface intervals.
- Under-bench lockers or shelves for dry bags and shoes.
Careful separation of wet and dry storage avoids the gradual creep of equipment into passages and emergency access routes.
Structural and regulatory considerations
Even when focused on deck layout, hull structure and regulatory context cannot be ignored. Kemenhub passenger approvals and local Syahbandar inspections sit alongside class or survey requirements where applicable.
We check that:
- Added loads from racks, compressors and fixed tanks are transmitted into primary structure.
- Escape routes and emergency exits remain compliant after fit-out.
- Liferaft, lifejacket and fire equipment stowage integrates without obstructing diver operations.
On timber hulls, we protect critical connection points with hardwood pads and through-bolting. On composite hulls, we may locally increase laminate thickness or add stringers, as informed by the build specification and intended survey regime.
From concept to working Gili dive boat
Designing a functional Gili dive boat is an iterative process between operator, builder and surveyor. We begin by documenting the number of divers per trip, turnover goals, preferred sites and boarding points. This leads to an initial general arrangement, which we refine through weight estimates and equipment selection.
Below is a simplified planning table for a typical new-build process for a 12–20 m dive boat operating from the Gili islands.
| Stage | Typical scope | Indicative duration (weeks) | Indicative cost band (USD) |
|---|---|---|---|
| 1. Operational brief | Routes, diver numbers, filling strategy, launch sites, mixed-use roles. | 1–2 | Included in design engagement |
| 2. Concept layout | General arrangement, tank rack options, ladder and entry plan. | 2–4 | 3,000–7,000 |
| 3. Detailed design | Structure, systems, compressor integration, electrical and plumbing. | 4–8 | 8,000–20,000 |
| 4. Construction | Hull, deck, superstructure, fit-out, paint and systems installation. | 16–36 | Indicatively 250,000–1,200,000 depending on size and spec |
| 5. Trials and approvals | Sea trials, adjustments, documentation for local authorities. | 2–6 | Variable; often budgeted as part of main build |
Actual figures depend on material choice, propulsion, equipment level and survey requirements. Some operators adapt fast-boat hulls for diving, drawing on experience from routes such as those described in the Bangsal–Gili fast boat specification. Others pursue a fully bespoke layout under a broader custom boat build programme.
Frequently asked questions
How many cylinders should a Gili dive boat be designed to carry?
Capacity planning starts from your maximum divers per trip, multiplied by the number of dives, plus guide and safety reserves. For example, 12–16 divers on a two-tank day often implies rack space for around 30–40 cylinders. We then confirm that this load, plus spares and compressor banks if any, sits within the hull’s safe working displacement.
Is an onboard compressor essential for Gili dive operations?
An onboard compressor is not mandatory but changes your logistics. Shore filling works if you have reliable access, enough cylinders, and short transits. An onboard unit reduces cylinder inventory and offers flexibility for extra dives, but adds weight, heat, cost and maintenance. The choice is best made after mapping your daily schedule and fuel bunkering options.
What hull type works best for a Gili dive boat?
Monohulls, catamarans and modified fast-boat forms can all work, provided the deck is purpose-designed for diving. Key criteria are deck area, stability with divers moving, comfortable motion at typical Gili sea states and practical boarding height at your usual pier or beach. The hull choice then guides tank rack positions, ladder configuration and engine installation.
Can a passenger fast boat be converted into a dedicated dive boat?
Many fast-boat hulls can be adapted, but a simple seat removal is rarely enough. We usually need to reinforce deck areas for tank racks, re-route passenger flows, reposition ladders and add camera and rinse facilities. Regulatory documentation may also need updating to reflect new use and equipment. A brief survey and concept layout study helps define what is feasible.
How long does it take to build a new Gili dive boat from scratch?
Indicative timelines for a 12–20 m dive boat range from around six to twelve months from signed specification to sea trials, depending on complexity, material and equipment lead times. Weather windows, surveyor availability and import logistics for engines and compressors also affect duration. Early decisions on layout and machinery help avoid delays later in the build.